Delirium Induced by Rapid Titration of Osilodrostat in a Patient With Cushing’s Disease

Posted on November 21, 2025 by MaryO

Abstract

Cushing’s disease frequently presents with psychiatric symptoms such as depression, anxiety, and cognitive impairment. Osilodrostat, an 11β-hydroxylase inhibitor, is used for persistent or recurrent cases, but rapid titration may precipitate adrenal insufficiency and psychiatric complications.

We report a woman in her early 40s with a history of major depressive disorder treated with clomipramine. After transsphenoidal surgery for Cushing’s disease, she remained hypercortisolemic, and hydrocortisone replacement was continued postoperatively for safety due to unstable cortisol secretion. Cortisol secretion was unstable, with day-to-day fluctuations. Osilodrostat was initiated at 2 mg/day. Shortly thereafter, urinary free cortisol (UFC) increased, and between days 3 and 5, she developed depressive symptoms, depersonalization, and suicidal ideation. These were judged to be related to cortisol elevation, and osilodrostat was rapidly titrated, reaching 40 mg/day by day 9. Depressive symptoms improved as UFC decreased. However, from day 9, she developed delirium with fluctuating consciousness, disorientation, purposeless hyperactivity, and stereotyped speech, peaking on days 10-12. During this period, blood pressure decreased, accompanied by tachycardia and fever. Infection and metabolic abnormalities were clinically excluded. Symptoms resolved spontaneously by day 14, with amnesia for the episode, and she was discharged on day 20 without recurrence.

This case illustrates a rare clinical course where depressive symptoms during cortisol elevation and delirium during cortisol reduction occurred sequentially in the same patient following rapid osilodrostat titration. The episode suggests that abrupt cortisol fluctuations may induce psychiatric symptoms even under hydrocortisone supplementation. Clinicians should avoid rapid titration and ensure close collaboration between endocrinology and psychiatry when psychiatric symptoms arise during treatment.

Introduction

Cushing’s disease is caused by an adrenocorticotropic hormone (ACTH) secreting pituitary adenoma, leading to chronic hypercortisolism. In addition to physical features such as central obesity, moon face, and hypertension, psychiatric symptoms including depression, anxiety, and cognitive impairment are frequently observed [1-3]. Depression occurs in 40-60% of patients and is associated with increased suicide risk. Anxiety and cognitive impairment are also common, and psychiatric symptoms may even precede the physical manifestations. Thus, psychiatrists may encounter such patients at an early stage, and it is clinically important to consider underlying endocrine disorders [1,3]. The first-line treatment is transsphenoidal surgery, but remission is not always achieved [4].

Osilodrostat, an oral 11β-hydroxylase inhibitor, is primarily used for the treatment of persistent or recurrent Cushing’s disease. By inhibiting cortisol synthesis, it effectively lowers circulating cortisol levels, thereby improving the clinical manifestations of hypercortisolism. The phase III LINC 3 trial demonstrated its efficacy [5], but adverse events such as adrenal insufficiency and psychiatric symptoms have been reported [6-8]. Acute adrenal insufficiency can present with hypotension, tachycardia, fever, and gastrointestinal symptoms, and in severe cases with impaired consciousness or delirium [9]. To minimize these risks, gradual titration in 2-mg increments at intervals of at least two weeks is recommended [6].

For monitoring treatment efficacy, urinary free cortisol (UFC) is widely used as a reliable marker reflecting total cortisol secretion over 24 hours and serves as a standard index of disease activity and treatment response [1,2].

Case Presentation

The patient was a 43-year-old woman with a history of major depressive disorder since her early twenties, treated mainly with clomipramine. Although she experienced recurrent episodes, she was able to continue working as a clinical psychologist, with occasional sick leave. Her past history included papillary thyroid carcinoma treated surgically, followed by hypothyroidism managed with levothyroxine 75 µg/day.

In her thirties, she developed treatment-resistant hypertension. In March 2024, inferior petrosal sinus sampling confirmed Cushing’s disease. In April 2024, she underwent transsphenoidal surgery and started hydrocortisone replacement at 30 mg/day. However, hypercortisolism and elevated ACTH persisted. Cortisol levels showed marked day-to-day fluctuations rather than being consistently elevated, and replacement therapy was continued for safety.

In June 2024, she was admitted to our endocrinology department because of persistent disease activity. Psychiatry was consulted due to her psychiatric history. At admission, she was alert, cooperative, and exhibited neither depressive nor psychotic symptoms. Clomipramine was continued. Physical examination revealed a BMI of 27.5, central obesity, moon face, and violaceous striae. Blood pressure was 155/105 mmHg. Routine chemistry and thyroid function were within normal limits. Endocrinological work-up confirmed persistent hypercortisolism: the 24-hour UFC was markedly elevated (409.2 µg/day; normal < 50 µg/day), midnight serum cortisol was inappropriately high (14.3 µg/dL; normally suppressed at night), and dexamethasone suppression testing failed to suppress morning cortisol (9.7 µg/dL after 0.5 mg dexamethasone). Corticotropin-releasing hormone stimulation testing demonstrated an exaggerated ACTH response (63.6 → 105.0 pg/mL), consistent with pituitary-dependent Cushing’s disease. Postoperative brain MRI showed only expected surgical changes without new lesions.

Figure 1 illustrates the clinical course in this case. Osilodrostat was initiated at 2 mg/day on day 1. UFC unexpectedly rose thereafter, and between days 3 and 5, she developed depressed mood, depersonalization, and suicidal ideation. These psychiatric symptoms were judged to be associated with increased cortisol secretion. Antidepressant adjustment was not attempted. Instead, priority was given to endocrine control, and osilodrostat was rapidly up-titrated. Although the risk of adrenal insufficiency was considered, treatment was deemed safe under hydrocortisone supplementation. By day 9, the dose of osilodrostat reached 40 mg/day, UFC decreased, and depressive symptoms improved.

Timeline-of-clinical-events-and-interventions-in-the-present-case.
Figure 1: Timeline of clinical events and interventions in the present case.

Panel (A) shows the osilodrostat dosage and 24-hour urinary free cortisol (UFC) levels; panel (B) depicts vital signs (sBP, systolic blood pressure; BT, body temperature); and panel (C) illustrates psychiatric symptoms and the dosages of antipsychotic medications, all plotted against treatment days.

However, from day 9 onward, delirium and psychomotor agitation emerged, peaking on days 10-12. She displayed fluctuating consciousness, global disorientation, impaired attention, purposeless hyperactivity, stereotyped behaviors, and repetitive utterances of meaningless numbers. She wandered barefoot and occasionally shouted fragmented phrases such as “Say you love me.” Anxiety and insomnia were prominent, but hallucinations and self-disturbances were absent.

At that time, her vital signs showed a decline in blood pressure from 155/105 mmHg to 125/59 mmHg, a pulse rate of 110/min, and a temperature of 38.3°C. Electrolytes and glucose were normal, and no inflammatory response or other signs of infection were detected. Because of marked psychomotor agitation, imaging and EEG were not performed. Risperidone and haloperidol were given but were ineffective.

At onset, the delirium was interpreted as a manifestation of hypercortisolism, partly because it occurred during a holiday when comprehensive evaluation was not feasible. Osilodrostat was therefore not reduced. As her symptoms improved spontaneously and she remained stable under hydrocortisone supplementation, the dose was maintained. Since the delirium resolved completely and did not recur, additional imaging or EEG was not performed.

By day 14, delirium had resolved, and the patient reported amnesia for the episode. No recurrence occurred, and she was discharged on day 20 at her and her family’s request. Outpatient follow-up confirmed stable status without recurrence of delirium.

Discussion

This case illustrates an unusual clinical course in which qualitatively distinct psychiatric symptoms appeared sequentially during rapid titration of osilodrostat. The initial depressive phase coincided with a transient rise in UFC and may have been related to unstable cortisol secretion that had already been observed prior to admission. Although not sufficient for a formal diagnosis, such variability is reminiscent of cyclical Cushing’s disease [10], which has also been associated with mood fluctuations [1,3]. Previous studies have demonstrated the link between hypercortisolism and depression [1,3], and our case is consistent with these findings during the early phase of treatment.

In contrast, the subsequent delirium phase was accompanied by hypotension, tachycardia, and fever, resembling adrenal insufficiency. Similar neuropsychiatric manifestations, including delirium and psychosis, have been described in previous reports of adrenal insufficiency [8,9]. However, unlike those cases, where symptoms typically emerged after drug withdrawal, delirium in our patient developed rapidly following dose escalation. This temporal pattern suggests that even transient cortisol reductions may precipitate acute neuropsychiatric symptoms.

Taken together, these observations both align with and extend prior findings linking cortisol dysregulation to psychiatric manifestations. Our case supports previous evidence that hypercortisolism is associated with depressive symptoms [1,3], whereas hypocortisolism predisposes to delirium or psychosis [8,9]. Importantly, it also highlights a dynamic aspect of this relationship: abrupt cortisol fluctuations themselves, regardless of direction, may transiently disrupt neuroendocrine homeostasis and trigger psychiatric symptoms. This interpretation is consistent with reports of cyclical Cushing’s disease showing alternating mood states [10], but it differs in that the fluctuation here was iatrogenic and temporally linked to rapid pharmacologic titration.

Pharmacological factors may have further amplified these effects. Clomipramine and antipsychotics such as haloperidol and risperidone are known to cause confusion or agitation, particularly under hormonal stress. It is therefore plausible that psychotropic drug interactions and cortisol fluctuations acted synergistically to produce the observed neuropsychiatric manifestations.

This report has several limitations. The onset of delirium occurred during a holiday, and severe agitation precluded blood sampling for serum cortisol, ACTH testing, or therapeutic steroid administration. Thus, strict diagnostic criteria for adrenal insufficiency could not be fulfilled. Nonetheless, the clinical presentation, with hypotension, tachycardia, fever, and altered consciousness, was consistent with an adrenal insufficiency-like state. Electrolytes, glucose, and inflammatory markers remained within normal limits, making infection or metabolic causes unlikely. However, structural or neurological contributors could not be completely excluded because imaging and EEG were not performed. Although the clinical picture resembled adrenal insufficiency, true adrenal crisis was unlikely given the normal electrolyte levels, spontaneous recovery, and maintained oral intake. Therefore, this episode may be better characterized as a state of functional adrenal dysregulation rather than frank adrenal insufficiency.

Conclusions

This case highlights a rare course in which depressive symptoms during cortisol elevation and delirium during cortisol reduction occurred sequentially in the same patient following rapid titration of osilodrostat. The episode suggests that even under hydrocortisone supplementation, abrupt cortisol fluctuations can induce psychiatric symptoms. However, because some observations were paradoxical and certain assessments could not be performed during the acute phase, these interpretations should be made with caution. The episode may represent a state of functional adrenal dysregulation rather than distinct phases of hyper- or hypocortisolism.

This case offers two clinical lessons. First, osilodrostat should be titrated gradually according to established guidelines. Second, if psychiatric symptoms arise during treatment, they are best managed through close collaboration between endocrinology and psychiatry.

References

  1. Pivonello R, Simeoli C, De Martino MC, et al.: Neuropsychiatric disorders in Cushing’s syndrome. Front Neurosci. 2015, 9:129. 10.3389/fnins.2015.00129
  2. Sharma ST, Nieman LK, Feelders RA: Cushing’s syndrome: epidemiology and developments in disease management. Clin Epidemiol. 2015, 7:281-93. 10.2147/CLEP.S44336
  3. Sonino N, Fava GA, Raffi AR, Boscaro M, Fallo F: Clinical correlates of major depression in Cushing’s disease. Psychopathology. 1998, 31:302-6. 10.1159/000029054
  4. Fleseriu M, Auchus R, Bancos I, et al.: Consensus on diagnosis and management of Cushing’s disease: a guideline update. Lancet Diabetes Endocrinol. 2021, 9:847-75. 10.1016/S2213-8587(21)00235-7
  5. Pivonello R, Fleseriy M, Newell-Price J, et al.: Efficacy and safety of osilodrostat in patients with Cushing’s disease (LINC 3): a multicentre phase 3 study with a double-blind, randomised withdrawal phase. Lancet Diabetes Endocrinol. 2020, 8:748-61. 10.1016/S2213-8587(20)30240-0
  6. U.S. Food and Drug Administration. Osilodrostat prescribing information. (2020). Accessed: October 18, 2025: https://www.accessdata.fda.gov/drugsatfda_docs/label/2020/212801s000lbl.pdf.
  7. Gadelha M, Bex M, Feelders RA, et al.: Randomized trial of osilodrostat for the treatment of Cushing disease. J Clin Endocrinol Metab. 2022, 107:e2882-95. 10.1210/clinem/dgac178
  8. Ekladios C, Khoury J, Mehr S, Feghali K: Osilodrostat-induced adrenal insufficiency in a patient with Cushing’s disease. Clin Case Rep. 2022, 10:e6607. 10.1002/ccr3.6607
  9. Arlt W: Society for Endocrinology endocrine emergency guidance: Emergency management of acute adrenal insufficiency (adrenal crisis) in adult patients. Endocr Connect. 2016, 5:G1-3. 10.1530/EC-16-0054
  10. Meinardi JR, Wolffenbuttel BH, Dullaart RP: Cyclic Cushing’s syndrome: a clinical challenge. Eur J Endocrinol. 2007, 157:245-54. 10.1530/EJE-07-0262

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Endogenous Cushing’s Syndrome Market Insights Highlight Expanding Outlook Till 2032

Posted on November 15, 2025 by MaryO

DelveInsight’s “Endogenous Cushing’s Syndrome Market Insights, Epidemiology, and Market Forecast-2032′′ report offers an in-depth understanding of the Endogenous Cushing’s Syndrome, historical and forecasted epidemiology as well as the Endogenous Cushing’s Syndrome market trends in the United States, EU4 (Germany, Spain, Italy, France) the United Kingdom and Japan.

The latest healthcare forecast report provides an in-depth analysis of Endogenous Cushing’s Syndrome, offering comprehensive insights into the Endogenous Cushing’s Syndrome revenue trends, prevalence, and treatment landscape. The report delves into key Endogenous Cushing’s Syndrome statistics, highlighting the current and projected market size, while examining the efficacy and development of emerging Endogenous Cushing’s Syndrome therapies. Additionally, we cover the landscape of Endogenous Cushing’s Syndrome clinical trials, providing an overview of ongoing and upcoming studies that are poised to shape the future of Endogenous Cushing’s Syndrome treatment. This report is an essential resource for understanding the market dynamics and the evolving therapeutic options within the Endogenous Cushing’s Syndrome space.

To Know in detail about the Endogenous Cushing’s Syndrome market outlook, drug uptake, treatment scenario and epidemiology trends, Click here; Endogenous Cushing’s Syndrome Market Forecast
https://www.delveinsight.com/sample-request/endogenous-cushings-syndrome-market?utm_source=openpr&utm_medium=pressrelease&utm_campaign=gpr

Some of the key facts of the Endogenous Cushing’s Syndrome Market Report:
• The Endogenous Cushing’s Syndrome market size is anticipated to grow with a significant CAGR during the study period (2019-2032)
• In December 2024, Corcept Therapeutics, a US-based biotechnology company, has announced positive long-term results from its Phase III trial evaluating relacorilant as a treatment for individuals with endogenous hypercortisolism (Cushing’s syndrome).
• In October 2024, Sparrow Pharmaceuticals, a clinical-stage biopharmaceutical company focused on developing targeted therapies for unmet needs in endocrinology and immunology, announced the completion of its Phase 2 RESCUE trial evaluating clofutriben, a selective HSD-1 inhibitor, for endogenous Cushing’s syndrome. All eligible participants who completed the trial opted to continue treatment in an open-label extension (OLE) protocol. Encouraging results from the trial have accelerated plans for the next phase of development, set to begin next year. Additionally, the FDA has granted Orphan Drug Designation to clofutriben for the treatment of endogenous Cushing’s syndrome.
• Key Endogenous Cushing’s Syndrome Companies: Cortendo AB, RECORDATI GROUP, HRA Pharma, Corcept Therapeutics, and others
• Key Endogenous Cushing’s Syndrome Therapies: Levoketconazole, osilodrostat, metyrapone, CORT125134, and others
• The Endogenous Cushing’s Syndrome market is expected to surge due to the disease’s increasing prevalence and awareness during the forecast period. Furthermore, launching various multiple-stage Endogenous Cushing’s Syndrome pipeline products will significantly revolutionize the Endogenous Cushing’s Syndrome market dynamics.
• Research by Scaroni et al. (2023) indicates that Cushing syndrome occurs at an incidence rate of 1.5 per 1,000,000 individuals annually and has a prevalence of around 60 per 1,000,000 individuals in Europe. In about 80% of cases, Cushing syndrome is caused by adrenocorticotrophic hormone (ACTH) hypersecretion, resulting in ACTH-dependent Cushing syndrome.
• Cushing’s syndrome can be caused by either ACTH-dependent (80% of cases) or ACTH-independent (20% of cases) factors. The latter is primarily attributed to benign adrenal tumors (60%) or malignant tumors (40%). ACTH overproduction can either originate from the pituitary (85% of cases) or result from ectopic tumor secretion (15% of cases). The term “Cushing’s disease” is specifically used to refer to ACTH-secreting pituitary tumors.

Endogenous Cushing’s Syndrome Overview
Endogenous Cushing’s Syndrome is a rare hormonal disorder caused by the body’s overproduction of cortisol, a hormone produced by the adrenal glands. This overproduction can result from tumors or abnormalities in the pituitary gland (Cushing’s disease), adrenal glands, or other parts of the body that cause excessive cortisol secretion. It contrasts with exogenous Cushing’s syndrome, which results from external sources like long-term use of corticosteroid medications.

Get a Free sample for the Endogenous Cushing’s Syndrome Market Forecast, Size & Share Analysis Report:
https://www.delveinsight.com/report-store/endogenous-cushings-syndrome-market?utm_source=openpr&utm_medium=pressrelease&utm_campaign=gpr

Endogenous Cushing’s Syndrome Epidemiology
The epidemiology section provides insights into the historical, current, and forecasted epidemiology trends in the seven major countries (7MM) from 2019 to 2032. It helps to recognize the causes of current and forecasted trends by exploring numerous studies and views of key opinion leaders. The epidemiology section also provides a detailed analysis of the diagnosed patient pool and future trends.

Endogenous Cushing’s Syndrome Epidemiology Segmentation:
The Endogenous Cushing’s Syndrome market report proffers epidemiological analysis for the study period 2019-2032 in the 7MM segmented into:
• Total Prevalence of Endogenous Cushing’s Syndrome
• Prevalent Cases of Endogenous Cushing’s Syndrome by severity
• Gender-specific Prevalence of Endogenous Cushing’s Syndrome
• Diagnosed Cases of Episodic and Chronic Endogenous Cushing’s Syndrome

Download the report to understand which factors are driving Endogenous Cushing’s Syndrome epidemiology trends @ Endogenous Cushing’s Syndrome Epidemiology Forecast
https://www.delveinsight.com/sample-request/endogenous-cushings-syndrome-market?utm_source=openpr&utm_medium=pressrelease&utm_campaign=gpr

Endogenous Cushing’s Syndrome Drugs Uptake and Pipeline Development Activities
The drugs uptake section focuses on the rate of uptake of the potential drugs recently launched in the Endogenous Cushing’s Syndrome market or expected to get launched during the study period. The analysis covers Endogenous Cushing’s Syndrome market uptake by drugs, patient uptake by therapies, and sales of each drug.
Moreover, the therapeutics assessment section helps understand the drugs with the most rapid uptake and the reasons behind the maximal use of the drugs. Additionally, it compares the drugs based on market share.
The report also covers the Endogenous Cushing’s Syndrome Pipeline Development Activities. It provides valuable insights about different therapeutic candidates in various stages and the key companies involved in developing targeted therapeutics. It also analyzes recent developments such as collaborations, acquisitions, mergers, licensing patent details, and other information for emerging therapies.

Endogenous Cushing’s Syndrome Therapies and Key Companies
• Levoketconazole: Cortendo AB
• osilodrostat: RECORDATI GROUP
• metyrapone: HRA Pharma
• CORT125134: Corcept Therapeutics

Discover more about therapies set to grab major Endogenous Cushing’s Syndrome market share @ Endogenous Cushing’s Syndrome Treatment Landscape
https://www.delveinsight.com/sample-request/endogenous-cushings-syndrome-market?utm_source=openpr&utm_medium=pressrelease&utm_campaign=gpr

Endogenous Cushing’s Syndrome Market Drivers
• Growing Prevalence of Endogenous Cushing’s Syndrome
• Advancements in Diagnostic Techniques
• Emerging Targeted Therapies
• Increasing Investment in Rare Disease Research
• Growing Awareness and Early Diagnosis
• Increased Focus on Orphan Drug Development

Endogenous Cushing’s Syndrome Market Barriers
• High Treatment Costs
• Limited Treatment Options
• Complexity in Diagnosis
• Side Effects of Current Treatments
• Small Patient Population
• Regulatory Challenges

Scope of the Endogenous Cushing’s Syndrome Market Report
• Study Period: 2019-2032
• Coverage: 7MM [The United States, EU5 (Germany, France, Italy, Spain, and the United Kingdom), and Japan]
• Key Endogenous Cushing’s Syndrome Companies: Cortendo AB, RECORDATI GROUP, HRA Pharma, Corcept Therapeutics, and others
• Key Endogenous Cushing’s Syndrome Therapies: Levoketconazole, osilodrostat, metyrapone, CORT125134, and others
• Endogenous Cushing’s Syndrome Therapeutic Assessment: Endogenous Cushing’s Syndrome current marketed and Endogenous Cushing’s Syndrome emerging therapies
• Endogenous Cushing’s Syndrome Market Dynamics: Endogenous Cushing’s Syndrome market drivers and Endogenous Cushing’s Syndrome market barriers
• Competitive Intelligence Analysis: SWOT analysis, PESTLE analysis, Porter’s five forces, BCG Matrix, Market entry strategies
• Endogenous Cushing’s Syndrome Unmet Needs, KOL’s views, Analyst’s views, Endogenous Cushing’s Syndrome Market Access and Reimbursement

Media Contact
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It also offers Healthcare Consulting Services, which benefits in market analysis to accelerate the business growth and overcome challenges with a practical approach.

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Enhanced Radiological Detection of a Corticotroph Adenoma Following Treatment With Osilodrostat

Posted on October 28, 2025 by MaryO

Abstract

In approximately 30% of patients with Cushing disease, pituitary magnetic resonance imaging (MRI) does not reliably identify a corticotroph adenoma. Importantly, surgical remission rates are >2.5 fold higher for microadenomas that are radiologically visible on preoperative imaging when compared with “MRI-negative” cases. We describe a 42-year-old woman with Cushing disease, in whom MRI findings at presentation were equivocal with no clear adenoma visualized. She was initially treated with metyrapone, which resulted in partial biochemical control of hypercortisolism. After switching to osilodrostat, there was a marked improvement in her symptoms and rapid normalization of cortisol levels. Following 3 months of eucortisolemia, [11C]methionine positron emission tomography (MET-PET) coregistered with volumetric MRI (MET-PET/MRCR) localized the site of the corticotroph tumor and the patient underwent successful transsphenoidal resection. She remains in full clinical and biochemical remission at >2 years postsurgery. This case suggests that a period of eucortisolemia induced by osilodrostat may facilitate localization of corticotroph microadenomas using functional (PET) imaging.

Cushing disease, osilodrostat, [11C]methionine PET, corticotroph adenoma
Issue Section:

Case Report

Introduction

Cushing disease, caused by an ACTH-secreting pituitary adenoma, accounts for approximately 80% of endogenous Cushing syndrome [1]. Although transsphenoidal surgery remains the preferred treatment for the majority of patients, even in expert centers recurrence rates as high as 27% have been reported [2, 3]. Surgery is preferred over medical therapy because it offers the potential for definitive cure by directly removing the pituitary adenoma. In contrast, medical therapy is typically reserved for patients in whom surgery is contraindicated, incomplete, or has failed to achieve remission. Linked to this, magnetic resonance imaging (MRI) fails to detect an adenoma in approximately one third of cases [4]. In a recent systematic review, postsurgical remission rates were 2.63-fold higher (95% CI, 2.06-3.35) for MRI-detected corticotroph adenomas when compared with “MRI-negative” cases [5]. Several alternative magnetic resonance sequences have therefore been proposed to aid tumor localization (including dynamic and volumetric [eg, gradient recalled echo MRI]), but these still fail to detect a significant proportion of microcorticotropinomas [6, 7]. Accordingly, molecular (functional) imaging with positron emission tomography (PET) radiotracers that target key properties of corticotroph adenomas (eg, [11C]methionine [MET-PET], [18F]fluoroethyltyrosine, or [68Ga]DOTA-corticotropin-releasing hormone PET) has been proposed as an additional tool for localizing corticotroph tumors that evade detection on conventional MRI [6-10].

Medical therapy is often required for patients in whom surgery is not an immediate option or when there is persistent hypercortisolism postoperatively [11]. Cortisol-lowering treatment may also be considered before surgery to reduce morbidity and perioperative complications [11]. An important recent addition to the armory of medications used to treat Cushing syndrome is osilodrostat, a potent oral inhibitor of the key adrenal steroidogenic enzyme 11β-hydroxylase [12, 13].

Here, we describe how preoperative medical therapy with osilodrostat yielded dual benefits in a patient with inconclusive primary imaging: (1) rapid and effective control of hypercortisolism and (2) facilitation of the localization of a previously occult microcorticotroph adenoma using MET-PET coregistered with volumetric MRI (MET-PET/MRCR).

Case Presentation

A 42-year-old woman presented with a 7-year history of progressive central weight gain, facial plethora, acne, worsening hypertension, depression, and proximal myopathy. Her symptoms had become more pronounced during the COVID-19 pandemic, leading to profound emotional distress and functional decline. She described feeling persistently tearful and fatigued, with markedly reduced energy levels that rendered her unable to work or care for her young child, and severely affecting her quality of life. She had no significant medical history and was taking amlodipine and the progesterone-only pill. On examination, her body mass index was 29.6 kg/m² and blood pressure was markedly elevated at 197/111 mm Hg. Clinical features consistent with hypercortisolism included easy bruising, centripetal adiposity, and proximal muscle wasting. Initial laboratory evaluation was unremarkable; however, her hemoglobin A1c was at the upper end of normal (41 mmol/mol or 5.9%).

Diagnostic Assessment

Biochemical testing confirmed ACTH-dependent Cushing syndrome (Table 1). Cortisol levels following overnight and 48-hour dexamethasone suppression were elevated at 8 µg/dL (SI: 219 nmol/L) and 16 µg/dL (SI: 434 nmol/L), respectively (reference range: < 1.8 µg/dL [SI: < 50 nmol/L]). Plasma ACTH concentrations ranged from 36 to 55 ng/L (SI: 7.9-12.1 pmol/L) (reference range: 10-30 ng/L [SI: 2.2-6.6 pmol/L]), consistent with an ACTH-driven process. Urinary free cortisol (UFC) was markedly elevated at 690.95 µg/24 hours (SI: 1907 nmol/24 hours) (reference range: 18-98 µg/24 hours [SI: 50-270 nmol/24 hours]). Late-night salivary cortisol and cortisone levels were also elevated at 0.95 µg/dL (SI: 26.2 nmol/L) (reference range: < 0.09 µg/dL [SI: < 2.6 nmol/L]) and 2.7 µg/dL (SI: 74.5 nmol/L) (reference range: < 0.7 µg/dL [SI: < 18 nmol/L]) respectively. Inferior petrosal sinus sampling excluded an ectopic source of ACTH production (central-to-peripheral ACTH ratio: baseline 18.60, 0 minutes 18.4, peak at 2 minutes 94.9, 5 minutes 42.4, 10 minutes 22.3) (Table 2). However, pituitary MRI findings were inconclusive, with no definite adenoma identified. In addition, the left intracavernous carotid artery encroached medially, creating a narrow intercarotid window with distortion of normal pituitary anatomy (Fig. 1). Given these findings, the decision was made to initiate cortisol-lowering therapy and to reassess imaging appearances after a period of biochemical normalization.

Pituitary MRI at initial presentation. No discrete adenoma is visible on T1-weighted coronal precontrast (A) and postcontrast (B), T2-weighted coronal (C), and T1-weighted sagittal postcontrast (D) sequences. The sellar anatomy appears asymmetric, consistent with a medially positioned left internal carotid artery.

Figure 1.

Pituitary MRI at initial presentation. No discrete adenoma is visible on T1-weighted coronal precontrast (A) and postcontrast (B), T2-weighted coronal (C), and T1-weighted sagittal postcontrast (D) sequences. The sellar anatomy appears asymmetric, consistent with a medially positioned left internal carotid artery.

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Table 1.

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Biochemical investigations at diagnosis confirming ACTH-dependent Cushing syndrome

Tests Results Reference Range
Overnight dexamethasone suppression test (ONDST) Cortisol: 8 µg/dL (SI: 219 nmol/L) <1.8 µg/dL (SI: < 50 nmol/L)
48-hour dexamethasone suppression test (DST) Cortisol: 16 µg/dL (SI: 434 nmol/L) <1.8 µg/dL (SI: < 50 nmol/L)
ACTH 36-55 ng/L (SI: 7.9-12.1 pmol/L) 10-30 ng/L (SI: 2.2-6.6 pmol/L)
24-hour urinary free cortisol (UFC) 690.95 μg/24 h (SI: 1907 nmol/24 h) 18-98 µg/24 h (SI: 50-270 nmol/24 hours)
Late-night salivary cortisol
late-night salivary cortisone		 0.95 µg/dL (SI: 26.2 nmol/L)
2.7 µg/dL (SI: 74.5 nmol/L)		 <0.09 µg/dL (SI: <2.6 nmol/L) <0.7 µg/dL (SI: <18 nmol/L)

Results are reported in both conventional and SI units with reference ranges shown in parentheses.

Table 2.

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Results of inferior petrosal sinus sampling (IPSS)

Time Plasma ACTH
(min) Left petrosal sinus Right petrosal sinus Peripheral vein
−5 1159 ng/L (255 pmol/L) 144 ng/L (32 pmol/L) 62.3 ng/L (14 pmol/L)
0 1147 ng/L (253 pmol/L) 222 ng/L (49 pmol/L) 62.3 ng/L (14 pmol/L)
2 5257 ng/L (1157 pmol/L) 2159 ng/L (475 pmol/L) 55.4 ng/L (12.2 pmol/L)
5 3677 ng/L (810 pmol/L) 2976 ng/L (655 pmol/L) 86.8 ng/L (19 pmol/L)
10 2251 ng/L (496 pmol/L) 545 ng/L (120 pmol/L) 101 ng/L (22 pmol/L)

Time Plasma cortisol
(min) Left petrosal sinus Right petrosal sinus Peripheral vein
−5 24.94 μg/dL (668 nmol/L) 25.30 μg/dL (698 nmol/L) 23.56 μg/dL (650 nmol/L)
0 25.08 μg/dL (692 nmol/L) 24.07 μg/dL (664 nmol/L) 23.34 μg/dL (644 nmol/L)
2 23.31 μg/dL (643 nmol/L) 24.32 μg/dL (671 nmol/L) 23.78 μg/dL (656 nmol/L)
5 21.97 μg/dL (606 nmol/L) 23.67 μg/dL (653 nmol/L) 23.23 μg/dL (641 nmol/L)
10 27.62 μg/dL (762 nmol/L) 26.17 μg/dL (722 nmol/L) 25.26 μg/dL (697 nmol/L)

Time Plasma prolactin
(min) Left petrosal sinus Right petrosal sinus Peripheral vein
−5 1835 mU/L (86 μg/L) 356 mU/L (17 μg/L) 251 mU/L (11 μg/L)
0 1725 mU/L (81 μg/L) 498 mU/L (23 μg/L) 248 mU/L (12 μg/L)
2 2151 mU/L (101 μg/L) 409 mU/L (19 μg/L) 240 mU/L (11 μg/L)
5 2239 mU/L (105 μg/L) 711 mU/L (33 μg/L) 246 mU/L (12 μg/L)
10 1883 mU/L (89 μg/L) 410 mU/L (19 μg/L) 244 mU/L (11 μg/L)

Central-to-peripheral ACTH gradients before and after corticotropin-releasing hormone (CRH) stimulation support a pituitary source of ACTH secretion. Reference cutoffs: basal ACTH gradient ≥2 and/or CRH-stimulated ACTH gradient ≥3 indicate central ACTH secretion.

Treatment

The patient was started on metyrapone, but despite dose escalation up to 4000 mg daily, which was associated with significant nausea and malaise, she did not achieve eucortisolemia (Fig. 2C). She was therefore transitioned to osilodrostat, which rapidly normalized cortisol levels within 5 weeks at a maintenance dose of 6 mg twice daily (Fig. 2B and 2C). In contrast to metyrapone, osilodrostat was well-tolerated with no reported side effects. Serum cortisol and clinical status were closely monitored throughout, with no biochemical or clinical evidence of adrenal insufficiency.

Bar charts illustrating changes in urinary, salivary, and serum cortisol, as well as serum ACTH, during medical treatment. (A) A 24-hour UFC (black bars, left y-axis) normalized during osilodrostat treatment, whereas serum ACTH (gray bars, right y-axis) increased. Dotted lines represent the upper limit of normal: 59.4 µg/24 hours (SI: 164 nmol/24 hours) for UFC and 30 ng/L (SI: 6.6 pmol/L) for ACTH. X-axis labels indicate treatment week and total daily osilodrostat dose. (B) Salivary free cortisol levels, collected alongside serum cortisol during a cortisol day curve (at 09:00, 12:00, 15:00, and 18:00), fully normalized with osilodrostat therapy. Bar shading from black to light gray denotes sampling time. The dotted line indicates upper limit of normal: 9.4 ng/dL (SI: 2.6 nmol/L). (C) Serum free cortisol levels during day curves showed inadequate control on escalating doses of metyrapone, with normalization achieved following initiation of osilodrostat.

Figure 2.

Bar charts illustrating changes in urinary, salivary, and serum cortisol, as well as serum ACTH, during medical treatment. (A) A 24-hour UFC (black bars, left y-axis) normalized during osilodrostat treatment, whereas serum ACTH (gray bars, right y-axis) increased. Dotted lines represent the upper limit of normal: 59.4 µg/24 hours (SI: 164 nmol/24 hours) for UFC and 30 ng/L (SI: 6.6 pmol/L) for ACTH. X-axis labels indicate treatment week and total daily osilodrostat dose. (B) Salivary free cortisol levels, collected alongside serum cortisol during a cortisol day curve (at 09:00, 12:00, 15:00, and 18:00), fully normalized with osilodrostat therapy. Bar shading from black to light gray denotes sampling time. The dotted line indicates upper limit of normal: 9.4 ng/dL (SI: 2.6 nmol/L). (C) Serum free cortisol levels during day curves showed inadequate control on escalating doses of metyrapone, with normalization achieved following initiation of osilodrostat.

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ACTH levels progressively increased as the dose of osilodrostat was escalated (Fig. 2A). After 3 months of biochemical eucortisolism, she underwent Met-PET/MRCR, which revealed a distinct methionine-avid lesion in the right posterolateral aspect of the sella (Fig. 3). Imaging was performed as previously reported [7, 8, 14]. Conventional MRI findings remained stable, with no new abnormalities. As she remained clinically and biochemically eucortisolemic on osilodrostat, glucocorticoid supplementation was not required pre- or perioperatively.

11C-Methionine PET/CT coregistered with volumetric MRI (MET-PET/MRCR) following treatment with osilodrostat. A subtle area of reduced gadolinium enhancement can now be appreciated on the right posterosuperior aspect of the gland (A-C). MET-PET/MRCR confirms focal tracer uptake at this site (yellow arrows) and also within normal gland anteriorly (white arrow) (D-F). Three-dimensional reconstruction using CT, MRI, and PET datasets demonstrating the location of the corticotroph microadenoma which was confirmed at subsequent surgery (G-H).

Figure 3.

11C-Methionine PET/CT coregistered with volumetric MRI (MET-PET/MRCR) following treatment with osilodrostat. A subtle area of reduced gadolinium enhancement can now be appreciated on the right posterosuperior aspect of the gland (A-C). MET-PET/MRCR confirms focal tracer uptake at this site (yellow arrows) and also within normal gland anteriorly (white arrow) (D-F). Three-dimensional reconstruction using CT, MRI, and PET datasets demonstrating the location of the corticotroph microadenoma which was confirmed at subsequent surgery (G-H).

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Outcome and Follow-up

At transsphenoidal surgery, abnormal tissue was resected from the site identified on MET-PET/MRCR. Histological examination revealed normal anterior pituitary tissue (adenohypophysis) with no evidence of a pituitary adenoma. Occasional cells showed possible Crooke’s hyaline change. The Ki-67 proliferation index was very low (<1%). Despite the absence of histological confirmation of a corticotroph adenoma, the patient entered complete biochemical and clinical remission. Early postoperative cortisol was 3 µg/dL (SI: 82.8 nmol/L), prompting initiation of glucocorticoid replacement with prednisolone. Prednisolone was chosen for its longer half-life, enabling convenient once-daily dosing. We routinely monitor prednisolone levels to guide adjustment of replacement dosing. Prednisolone was successfully tapered over a period of 6 months, with biochemical confirmation of adrenal recovery. At 2 years postsurgery, the patient had no clinical features of hypercortisolism with sustained weight loss of >20 kg. Morning 09:00 cortisol and ACTH were consistent with ongoing eucortisolism. Serial late-night salivary cortisol and cortisone levels were normal, and cortisol was undetectable following a 1-mg overnight dexamethasone suppression test, confirming durable remission of Cushing disease.

Discussion

Early transsphenoidal surgery remains the treatment of choice for most patients with Cushing disease, with the highest chance of cure achieved following a successful first operation [11]. However, even in expert centers, persistent or recurrent disease is diagnosed during follow-up, and is more likely when initial MRI has failed to identify a clear surgical target [5]. Reoperation carries increased technical difficulty and a higher risk of iatrogenic hypopituitarism, underscoring the importance of accurate preoperative localization of corticotroph adenomas. Our case illustrates a potential novel added benefit of a trial of primary medical therapy in a patient with Cushing disease and equivocal or negative MRI findings at initial presentation. Specifically, we have shown how osilodrostat, a potent inhibitor of 11β-hydroxylase, can achieve rapid normalization of cortisol levels, consistent with the findings of the LINC (LCI699 [osilodrostat] in Cushing disease) series of studies [15-17], and at the same time help reveal the location of the occult microcorticotropinoma. An important consequence of achieving effective adrenal blockade in our patient was the more than threefold accompanying rise in plasma ACTH levels (Fig. 2). We hypothesized that such an increase in tumoral activity might facilitate its detection using molecular (functional) imaging. MET-PET has been shown in several studies to facilitate localization of de novo and recurrent corticotroph adenomas [8, 18, 19] in a significant proportion of patients with equivocal or negative MRI findings. We have now shown that such an approach could potentially be enhanced by pretreatment with the potent 11β-hydroxylase inhibitor osilodrostat.

We also considered whether the rise in ACTH during osilodrostat therapy reflected increased tumor activity alone or was associated with a change in tumor size. In our case, ACTH rose significantly, likely reflecting enhanced secretory activity, whereas repeat conventional MRI remained stable, with no new abnormalities or interval changes. In the LINC 4 study, tumor volume data were available for 35 patients at both baseline and week 48. Among these, 40.0% had a ≥20% increase, 28.6% had a ≥20% decrease, and 31.4% had <20% change in tumor volume. These outcomes were observed in both microadenomas and macroadenomas, with no clear correlation to treatment duration or osilodrostat dose [20]. This variability suggests that osilodrostat does not exert a consistent effect on tumor volume.

Interestingly, although histopathological analysis did not confirm a corticotroph adenoma, this is a well-recognized finding and has been reported in a significant proportion of patients undergoing surgery for Cushing disease [21, 22]. Nonetheless, we consider the diagnosis of pituitary-dependent Cushing syndrome was clearly established by the clinical features, results of initial laboratory testing and findings at inferior petrosal sinus sampling (which demonstrated a clear central-to-peripheral ACTH gradient). In addition, abnormal tissue was identified intraoperatively at the site visualized on MET-PET and fully resected, and no other abnormal foci of tissue were seen. The patient has subsequently achieved complete and sustained clinical and biochemical remission, consistent with successful removal of an ACTH-secreting adenoma.

Recent case reports have raised concerns about prolonged adrenal insufficiency following extended osilodrostat use—an unexpected finding given the drug’s short half-life [23-25]. Although adrenal insufficiency requiring temporary glucocorticoid replacement had been reported in clinical trials (most commonly in patients undergoing rapid dose escalation [12, 15, 16]), prolonged hypothalamopituitary-adrenal axis suppression resulting from supraphysiologic glucocorticoid replacement could also be contributory. For now, the exact mechanism of this observed phenomenon remains unclear. Our patient managed to wean glucocorticoid replacement postoperatively and did not demonstrate prolonged adrenal suppression; at the same time, clinical and biochemical testing confirmed full remission from Cushing disease.

This case supports the hypothesis that preoperative cortisol suppression may enhance the diagnostic accuracy of molecular (functional) imaging in Cushing disease, particularly in cases with inconclusive MRI findings. If validated in prospective studies, this approach could refine surgical planning and potentially lead to better surgical success and durable clinical outcomes.

Learning Points

  • Approximately 30% of corticotroph adenomas causing Cushing disease are not readily localized on conventional pituitary MRI.

  • Functional imaging modalities such as MET-PET/MRCR can improve detection of previously occult pituitary adenomas in Cushing disease.

  • A period of medical pretreatment with osilodrostat, with consequent reduction in negative feedback by glucocorticoid at the hypothalamic-pituitary level, may augment tumor localization by molecular imaging.

Acknowledgments

The authors acknowledge Debbie Papadopoulou and Niamh Martin for their contributions to clinical management. Nigel Mendoza performed the transsphenoidal surgery.

Contributors

All authors made individual contributions to authorship. Z.H., L.Y., J.M., M.G., and F.W. were involved in the diagnosis and management of this patient and manuscript submission. J.M., D.G., and M.G. performed and analyzed the patient’s functional imaging. All authors reviewed and approved the final draft.

Funding

No public or commercial funding

Disclosures

None declared.

Informed Patient Consent for Publication

Signed informed consent obtained directly from the patient.

Data Availability Statement

Original data generated and analyzed during this study are included in this published article.

© The Author(s) 2025. Published by Oxford University Press on behalf of the Endocrine Society.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited. See the journal About page for additional terms.

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Osilodrostat for Cyclic Cushing’s Disease

Posted on October 24, 2025 by MaryO

Highlights

  • •
    Cyclic Cushing’s syndrome (CCS) is a rare entity with significant comorbidities
  • •
    It is defined by at least 3 peaks of hypercortisolism, 2 troughs of eucortisolism
  • •
    Surgical cure is preferred, and medications are second-line
  • •
    Our case is the first showing successful treatment of native CCS with osilodrostat
  • •
    Osilodrostat showed rapid onset/offset and reversible inhibition of steroidogenesis

Abstract

Background/Objective

Cyclic Cushing’s syndrome is a rare subtype of Cushing’s syndrome with episodes of hypercortisolism, followed by spontaneous remission.

Case Report

Our patient was a 68-year-old male who presented with his third cycle of cyclic Cushing’s disease with facial swelling, buffalo hump, fatigue, proximal muscle weakness, and lower extremity edema. Laboratory tests showed the following: 24-hour urine free cortisol 12030.3 mcg/d (normal <= 60.0 mcg/d), morning adrenocorticotropic hormone (ACTH) 464 pg/mL (normal 6-59 pg/mL), morning serum cortisol 91 mcg/dL (normal 8-25 mcg/dL), and potassium 3.3 mmol/L (normal 3.6-5.3 mmol/L). MRI pituitary without/with contrast showed a partially empty sella. Prior inferior petrosal sinus sampling during the second cycle indicated a potential pituitary source of increased ACTH production, localized or draining to the right side. The patient was treated with osilodrostat with improvement in laboratory values and clinical symptoms by 2-3 weeks. After development of adrenal insufficiency (AI), osilodrostat was rapidly titrated off by 2 months of treatment. Subsequently, labs after 8 days off osilodrostat confirmed clinical remission and reversibility of medication-induced AI.

Discussion

Since hypercortisolism is associated with mortality risk and comorbidities, timely management is a priority. If a surgical cure is not possible, a medication that treats hypercortisolism with rapid onset, reversible inhibition, and minimal side effects would be ideal to address the cyclicity.

Conclusion

Our case is the first to our knowledge demonstrating osilodrostat’s use for native cyclic Cushing’s syndrome treatment and highlighted its reversibility and ability to preserve normal adrenal function.

Keywords

Osilodrostat
cyclic Cushing’s disease
cyclic Cushing’s syndrome

Introduction

Cyclic Cushing’s syndrome is a rare entity that represents a clinical challenge. It is defined by at least 3 peaks of biochemical hypercortisolism, which is clinically symptomatic in the majority though rarely asymptomatic, and 2 troughs with normalized cortisol production that can last from days to years.1 The phenomenon can arise from any potential source of Cushing’s syndrome, including pituitary (54%), ectopic (26%), adrenal (11%), and unclassified (9%) sources.1 Intermittent hypercortisolism can also occur after pituitary surgery for Cushing’s disease.2
The cyclicity interferes with a straightforward diagnosis. It can lead to paradoxical results from biochemical testing and inferior petrosal sinus sampling (IPSS),3 making determination of therapeutic outcomes more complicated.3 The goal of cyclic Cushing’s syndrome management, as in all types of Cushing’s syndrome, is early diagnosis and intervention to reduce the length of hypercortisolism.4 A surgical cure is preferred, as Cushing’s syndrome is associated with a five-fold increased standardized mortality risk.4 Cardiovascular, metabolic, bone, and cognitive comorbidities may persist despite remission and must be aggressively managed.4,5 For patients in whom surgical management is not possible or has not led to remission, medical therapy has a crucial role. We describe the first case to our knowledge of native cyclic Cushing’s syndrome treated successfully with osilodrostat. A case of exogenous cyclic ACTH-independent Cushing’s syndrome from pembrolizumab, with cyclicity attributed to the infusions, also demonstrated successful treatment with osilodrostat.6

Case Report

The patient was a 68-year-old male with hypertension, hyperlipidemia, and rheumatoid arthritis with a history of cyclical episodes of weight gain and facial swelling, occurring spontaneously without steroid treatments. The initial episode occurred at age 62 for 5 months, and returned at age 64 with facial swelling, buffalo hump, fatigue, proximal muscle weakness, sleep disturbances, and lower extremity edema. Laboratory tests showed the following (Table 1): 24-hour urine free cortisol >245 mcg/d (normal 11-84 mcg/d), morning adrenocorticotropic hormone (ACTH) 528.0 pg/mL (normal 7.2-63.3 pg/mL) and morning serum cortisol 91.7 mcg/dL (confirmed on dilution; normal 6.2-19.4 mcg/dL). Laboratory tests were also notable for a mildly low potassium level, low prolactin, low testosterone, and normal thyroid hormone, insulin-like growth factor-1 (IGF-1), and dehydroepiandrosterone sulfate (DHEA-S) levels. MRI pituitary without/with contrast showed no sellar and suprasellar masses. A prior CT abdomen/pelvis with contrast at age 62 noted unremarkable adrenal glands. The patient was referred for inferior petrosal sinus sampling (IPSS) (Table 2), which indicated a potential pituitary source of increased ACTH production, localized or draining to the right side. The central to peripheral gradient was >2 in the first pre-stimulation sample and >3 in all samples after providing 10mcg of desmopressin (DDAVP). There was a >1.4/1 gradient between the right and left sides, suggesting a potential pituitary source draining to the right side (Table 2). The inferior petrosal sinuses were normal and of similar size. Cushing’s symptoms receded spontaneously in 5 months, and the patient did not follow up until recurrence at age 67.

Table 1. Labs at time of onset of cyclical episodes

Empty Cell Labs at age 64 y/o (2nd episode) Labs at age 67 y/o (3rd episode)
24hr urine free cortisol level >245 mcg/24hr (normal 11-85 mcg/24hr) 12030.3 mcg/d (normal <= 60.0 mcg/d)
24hr urine creatinine 1495 mg/24hr (normal 1000-2000mg/24hr) 1868 mg/day (normal 800-2100 mg/day)
Morning ACTH 528.0 pg/mL (normal 7.2-63.3 pg/mL) 464 pg/mL (normal 6-59 pg/mL),
Morning cortisol 91.7 mcg/dL (normal 6.2-19.4 mcg/dL) 91 mcg/dL (normal 8-25 mcg/dL)
Thyroid-stimulating hormone level (TSH) 0.452 mcIU/mL (normal 0.450-4.500 mcIU/mL) 0.08 mcIU/mL (normal 0.3-4.7 mcIU/mL)
Free thyroxine (free T4) 1.34 ng/dL (normal 0.82-1.77 ng/dL) 1.30 ng/dL (normal 0.8-1.7 ng/dL)
Prolactin <1.0 ng/mL (normal 3.0-15.2 ng/mL) 8.05 ng/mL (normal 3.5-19.4 ng/mL)
Insulin-like growth factor-1 (IGF-1) 148 ng/mL (normal 64-240 ng/mL) 128 ng/mL (normal 41-279 ng/mL)_
Testosterone panel Total 66 ng/dL(11AM)
(normal 264-916 ng/dL)
Free 9.6 pg/mL (11AM)
(normal 6.6-18.1 pg/mL)		 Total 107 ng/dL (8:30AM)
(normal 300-720 ng/dL)
Bioavailable 61 ng/mL (8:30AM)
(normal 131-682 ng/mL)
Follicle-Stimulation Hormone (FSH) 3.6 mIU/mL (normal 1.6-9 mIU/mL)
Luteinizing Hormone (LH) 1.6 mIU/mL (normal 2-12 mIU/mL)
Dehydroepiandrosterone sulfate (DHEA-S) 153 mcg/dL (normal 48.9-344.2 mcg/dL)
Potassium level 3.2 mmol/L (normal 3.4-4.8 mmol/L) 3.3 mmol/L (normal 3.6-5.3 mmol/L)
Creatinine level 0.92 mg/dL (normal 0.7-1.2 mg/dL) 0.89 mg/dL (normal 0.6-1.3 mg/dL)

Table 2. Inferior Petrosal Sinus Sampling (IPSS)

Empty Cell Time Right IPS
ACTH level (normal 6-59 pg/mL)		 Left IPS
ACTH level (normal 6-59 pg/mL)		 Inferior Vena Cava ACTH level (normal 6-59 pg/mL) Serum Cortisol (normal 8-25 mcg/dL)
Baseline 1 08:25 AM 32 23 14 7
Baseline 2 08:27 AM 19 16 13 7
Desmopressin (DDAVP) 08:30 AM
Post 2 min 08:32 AM 150 34 15
Post 5 min 08:35 AM 123 32 18
Post 10 min 08:40 AM 49 26 17
Post 15 min 08:45 AM 124 31 17
Post 30 min 09:00 AM 107 28 13
*These results may indicate a pituitary source for increased ACTH production, localized or draining to the right side. There is a Central:Peripheral gradient of >2 (right IPS) in the first pre-stimulation samples and >3 in all post-desmopressin (DDAVP) 10mcg samples. If due to an adenoma, it might drain into the right given the presence of a significant (greater than 1.4/1) gradient between right and left. The inferior petrosal sinuses were of similar size and normal. These results must take into account the patient’s clinical scenario, and there are false positives and possible overlap with normal results.
*Abbreviation: min = minutes
During the third and most recent cycle of Cushing’s syndrome, laboratory tests after 1 month of symptom development showed the following (Table 1): 24-hour urine free cortisol 12030.3 mcg/d (normal <= 60.0 mcg/d), morning ACTH 464 pg/mL (normal 6-59 pg/mL), morning serum cortisol 91 mcg/dL (normal 8-25 mcg/dL), potassium level 3.3 mmol/L (normal 3.6-5.3 mmol/L), and mild leukocytosis and erythrocytosis. Repeat MRI pituitary without/with contrast showed a partially empty sella and no pituitary mass (Figure 1).

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Figure 1. MRI pituitary without/with contrast at the time of the third cyclical episode of Cushing’s disease. The MRI showed a partially empty sella with no evidence of a pituitary mass. Left) Coronal view. Right) Sagittal view.

The patient was started on osilodrostat 2mg twice daily. By week 2 of treatment, the morning cortisol level improved to 9.5 mcg/dL (8-25 mcg/dL) and potassium level normalized, though facial and body swelling persisted. Significant improvement in symptoms and fatigue were noted by week 3 of treatment with the following labs: morning ACTH 145 pg/mL (normal 6-59 pg/mL), morning serum cortisol 5.4 mcg/dL (8-25 mcg/dL), and 24-hour urine free cortisol 7 mcg/d (normal 5-64 mcg/d). The osilodrostat dose was decreased to 1mg twice daily, then 1mg daily, and stopped by 2 months of treatment after development of adrenal insufficiency (AI), which was confirmed on laboratory results (Table 3), along with corresponding symptoms of nausea, abdominal pain, low appetite, and fatigue. By that time, the facial and body swelling had also resolved. Potassium levels remained normal throughout treatment. After eight days off osilodrostat, laboratory tests showed the following: Noon ACTH 67 pg/mL (normal 6-59 pg/mL), noon serum cortisol 7.24 mcg/dL (normal 8-25 mcg/dL), and 24-hour urine free cortisol 26.2 mcg/d (normal <=60.0 mcg/d). Nearly 3 months off osilodrostat, the patient had an 11 AM ACTH of 68.9 pg/mL (normal 7.2-63.3 pg/mL) and 11AM serum cortisol level of 11.0 ug/dL (6.2-19.4 ug/dL). The clinical course is summarized in Table 3 and Figure 2. A DOTATATE-PET scan was discussed, though the patient wished to reconsider in the future given clinical response.

Table 3. Labs during treatment (Tx) with osilodrostat

Empty Cell 1 month before Tx Week 2 on Tx Week 3 on Tx Week 7 on Tx Week 9 on Tx – Tx stopped Week 1 off Tx Month 3 off Tx
Treatment with osilodrostat None On 2mg BID since Week 0 of Tx Advised to decrease to 1mg BID but patient did not decrease dose. Decreased to 1mg BID Decreased to 1mg daily after serum lab resulted. Then discontinued Tx after 24hr UFC resulted in several days. None None
ACTH level (pg/mL) 464 145 126 135 67 68.9
Cortisol level (mcg/dL) 91
8:32AM		 9.5
7:04AM		 5.4
7:11AM		 3.04
11:56AM		 4.9
11:26AM		 7.24
12:14PM		 11
11:08AM
24hr urine free cortisol (UFC) level (mcg/day) 12030.3 7 14 26.2
*Normal reference ranges depending on assays:
ACTH: 6-59 pg/mL or 7.2-63.3 pg/mL
Serum morning cortisol: 8-25 mcg/dL or 6.2-19.4 mcg/dL
24hr urine free cortisol: <=60.0 mcg/day or 5-64 mcg/day
*Acronyms: Tx = treatment; BID = twice daily; UFC = urine free cortisol, ACTH = adrenocorticotropic hormone

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Figure 2. Trends of 24hr urine cortisol levels and serum cortisol levels with osilodrostat treatment (Tx)

Discussion

Cyclic Cushing’s syndrome is a rare subtype of Cushing’s and occurs in both ACTH-dependent and ACTH-independent cases.3,7 Cyclicity has been attributed to hypothalamic dysfunction exaggerating a normal variant of hormonal cyclicity, a dysregulated positive feedback mechanism followed by negative feedback, intra-tumoral bleeding, and ACTH-secretion from neuroendocrine tumors (ex carcinoid tumors, pheochromocytomas).7,8,9,10
Potentially curative pituitary surgery or unilateral adrenalectomy are the treatments of choice.4 For example, cases of cyclic Cushing’s in primary pigmented nodular adrenocortical disease have demonstrated cure in some patients with unilateral adrenalectomy.11 In florid Cushing’s syndrome that is not amenable or responsive to other treatments, bilateral adrenalectomy could be lifesaving, though risks significant comorbidities including Nelson’s syndrome.4,12 Pituitary radiotherapy/radiosurgery are treatment options, though risks progressive anterior pituitary dysfunction.4 Medical therapy can play an important role as a bridge to surgery or radiation, with recurrence, for poor surgical candidates, or when there is no identifiable source as in our patient.13 Cyclic Cushing’s syndrome, moreover, has a higher recurrence rate (63%) and lower remission rate (25%), compared to classic Cushing’s syndrome.8
Medical treatments of cyclic Cushing’s syndrome include steroidogenesis inhibitors (ketoconazole, levoketoconazole, metyrapone, and osilodrostat), adrenolytic agents (mitotane), glucocorticoid receptor blockers (mifepristone), and pituitary tumor-directed agents (pasireotide, cabergoline, and temozolomide).8,14,15 Treatment goal is normalization of 24-hour urine cortisol levels and morning serum cortisol levels, though block-and-replace regimens occasionally are used.13,14 A block-and-replace regimen with osilodrostat and dexamethasone was used in the case of exogenous cyclic Cushing’s from pembrolizumab, given need for the immunotherapy;6 however, this regimen would hinder assessment of remission in native cyclic Cushing’s.
As our patient had cyclic Cushing’s disease, pituitary tumor-directed medications could be used for treatment. Pasireotide and cabergoline, however, are limited by a significant percentage of non-responders, along with risk of hyperglycemia for pasireotide.15 We considered mifepristone, which is a competitive antagonist at the glucocorticoid receptor and progesterone receptor; however, mifepristone is limited by the inability to directly monitor cortisol response on labs, in addition to the risk of AI and mineralocorticoid side effects with overtreatment.16
Steroidogenesis inhibitors block one or more enzymes in the production of cortisol, with potential risk of AI. The new steroidogenesis inhibitor osilodrostat, like metyrapone, selectively inhibits CYP11B1 and CYP11B2, which are involved in the final steps of cortisol and aldosterone synthesis, respectively.13,14 Ketoconazole and levoketoconazole, on the other hand, block most enzymes in the adrenal steroidogenesis pathway, including CYP11B1 and CYP11B2, and are limited by their inhibition of CYP7A (with associated hepatotoxicity) and strong inhibition of cytochrome p450 CYP3A4 (leading to many drug-drug interactions, decreased testosterone production, and QTc prolongation).14
Osilodrostat and metyrapone do not affect CYP7A and less potently inhibit CYP3A4.13 However, they can lead to increased deoxycorticosterone levels, with associated risks of hypokalemia, hypertension, and edema, and increased androgen production (with metyrapone thus being considered second-line in women).13,14,17
Osilodrostat, compared to metyrapone and ketoconazole, has a higher potency in CYP11B1 and CYP11B2 inhibition and a longer half-life, with stronger effects in lowering cortisol levels, allowance of less frequent (twice daily) dosing, and possibly less side effects.13,14,17,18 Compared to metyrapone, studies have suggested osilodrostat leads to a lesser rise in 11-deoxycortisol levels and less hyperandrogenic effects.13,14 Osilodrostat is also rapidly absorbed with sustained efficacy up to 6.7 years.17,18 Though rare cases of prolonged AI following discontinuation exist, osilodrostat (like other steroidogenesis inhibitors) is generally considered a reversible inhibitor.19 Reversible inhibition of cortisol synthesis is particularly appealing to treatment of cyclic Cushing’s syndrome as patients will not suffer from prolonged AI after episodes subside.
We thus considered osilodrostat an attractive treatment of cyclic Cushing’s syndrome. In our patient, osilodrostat was efficacious and well-tolerated, consistent with the literature,17 with clinical effects within 2-3 weeks without significant mineralocorticoid side effects. Differentiation of AI as a side effect of osilodrostat or from remission of the cyclical episode is crucial. Our patient was carefully tapered off osilodrostat after developing AI, and reversal of AI and osilodrostat inhibition were clearly demonstrated after 8 days off osilodrostat. Off treatment, the patient demonstrated neither prolonged AI nor clinical hypercortisolism, confirming remission of cyclic Cushing’s.

Conclusion

We present the first case to our knowledge demonstrating successful treatment of cyclic Cushing’s syndrome with osilodrostat. Osilodrostat showed rapid and safe control of hypercortisolism and importantly exhibited quick reversible inhibition of steroidogenesis upon discontinuation, a virtue in cyclic Cushing’s syndrome management.

References

Cited by (0)

The authors declare the following:
This paper did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
All authors do not have any conflicts of interests regarding the manuscript.
Run Yu, MD, PhD runyu@mednet.ucla.edu
Clinical Relevance
Osilodrostat is a new steroidogenesis inhibitor. Our case demonstrates the first successful treatment of native cyclic Cushing’s syndrome with osilodrostat, which showed rapid onset/offset, clinical safety, and reversible inhibition of steroidogenesis and medication-induced adrenal insufficiency. Osilodrostat’s preservation of underlying adrenal function is key when the cyclic Cushing’s episode spontaneously remits.

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Osilodrostat-associated Adrenal Gland Shrinkage: a Case Series of Patients with ACTH-Dependent Cushing’s Syndrome

Posted on October 18, 2025 by MaryO

The Journal of Clinical Endocrinology & Metabolism, dgaf552, https://doi.org/10.1210/clinem/dgaf552

Abstract

Context

Medical therapy for Cushing’s syndrome (CS) is increasingly used. A potent adrenal steroidogenesis inhibitor, osilodrostat, has been rarely linked to prolonged adrenal insufficiency (AI).

Objective

We hypothesized that osilodrostat-induced adrenal insufficiency could be associated with adrenal gland shrinkage.

Design

Non-interventional, retrospective, longitudinal, IRB-approved study of patients with CS treated at Oregon Health and Science University between January 1, 2000 and July 1, 2025.

Setting

Ambulatory and inpatient, academic, quaternary medical center.

Patients or Other Participants

Patients with ACTH-dependent CS, treated with osilodrostat for >3 months, and CT imaging before and after osilodrostat available for adrenal volume (AV) measurement.

Intervention(s)

Age, sex, osilodrostat doses and duration, laboratory data and AI were recorded. AV was calculated using manual segmentation on CT images by a board-certified radiologist.

Main Outcome Measure(s)

AV before and after initiation of osilodrostat was expressed as percent reduction.

Results

10 patients (5 ectopic CS, 4 unknown ACTH source, 1 Cushing’s disease) were included. Osilodrostat mean starting, maximum and final doses: 7.7, 13.8 and 5.9 mg/day, respectively, over 23 months. Four patients received block-and-replace regimen, AI developed in 5. Adrenal gland volume decreased by 46.7±22.2% from 25.5±9.9 ml to 12.7±6.4 ml, p<0.001 over a median of 19 months. AV reduction positively correlated with maximum osilodrostat dose, r=0.626, p=0.027.

Conclusions

We found that in selected patients with ACTH-dependent CS, osilodrostat can induce significant adrenal shrinkage, with or without AI. Further confirmation by larger studies of different CS types and monitoring for AI is required for all patients.

Filed under: adrenal, Cushing's, Treatments | Tagged: , , | Leave a comment »

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