Using the Desmopressin Stimulation Test to Assess for Residual Tumor in Cushing Disease With Cyclic Hypercortisolism

Posted on October 26, 2025 by MaryO

Abstract

Cushing disease is caused by excess ACTH secretion by a pituitary adenoma leading to hypercortisolism. Cyclic Cushing syndrome, in which periods of cortisol excess are interspersed by periods of normal or low values, poses a challenge to diagnostic testing and postoperative monitoring. We present a 26-year-old woman with cyclic Cushing syndrome who achieved apparent biochemical remission after transsphenoidal resection of an ACTH-producing pituitary tumor, confirmed on pathology. Despite initial clinical improvement, she later experienced recurring symptoms. Biochemical evidence of hypercortisolism was documented, but 1 month later morning serum cortisol was undetectable. A desmopressin stimulation test (DesST) produced a rise in ACTH and cortisol, indicating likely residual tumor tissue. After repeat surgery, pathology again confirmed an ACTH-secreting tumor. Postoperatively, ACTH and cortisol levels were again low, but a repeat DesST was now negative, suggesting successful resection of the residual tumor, and she remains in remission 3 years later. This case describes the unique utility of the DesST to detect a pituitary corticotroph tumor in cyclic Cushing disease during periods of low disease activity. It also highlights the potential role of the DesST in postoperative monitoring.

Cushing disease, cyclic Cushing, desmopressin stimulation test
Issue Section:

Case Report

Introduction

Cushing disease (CD), in which excess ACTH from a pituitary adenoma drives hypercortisolism, causes up to 70% of endogenous Cushing syndrome (CS) [1]. When possible, the first-line treatment for CD is transsphenoidal surgery (TSS) to remove the causative tumor. This leads to remission in approximately 80% of cases, with recurrence rates estimated at 20% [2].

Cyclic CS, in which periods of excess cortisol are interspersed with periods of normal or low cortisol, complicates both the initial diagnosis of CS and the interpretation of post-TSS hormone levels [3]. Basal ACTH and cortisol, and dexamethasone suppression tests performed during a period of low disease activity, can be misleading because they reflect healthy pituitary corticotrophs that are responsive to and suppressed by persistent hypercortisolism [4]. The same mechanism of corticotroph suppression pertains after TSS, so that very low morning plasma ACTH and serum cortisol levels (generally less than 10 pg/mL [SI: 2.2 pmol/L] and 5 µg/dL [SI: 138 nmol/L], respectively), indicate successful tumor resection [5, 6]. However, if postoperative testing occurs during a period of low disease activity in cyclic CS, it may falsely indicate remission.

The desmopressin stimulation test (DesST), in which ACTH and cortisol levels are measured following intravenous administration of 10 µg desmopressin, may help to resolve these problems. Most corticotroph adenomas respond to desmopressin with an increase in ACTH secretion, followed by a cortisol increase [7, 8]. By contrast, most healthy people do not respond. Desmopressin, a synthetic analogue of arginine vasopressin (AVP), is believed to trigger this response by binding to upregulated V3 receptors or ectopically expressed V2 receptors on corticotroph adenomas [9]. Some of the most commonly used response criteria for the DesST, ≥35% and ≥20% increases in ACTH and cortisol, respectively, are based on thresholds that produce high performance for the CRH stimulation test [10]. Currently, however, there is no clear consensus on optimal cutoffs for the DesST [9].

The return of a positive DesST response has been shown to precede the return of hypercortisolism when monitoring for recurrence of CD [11]. By analogy, we postulated that a postoperative DesST might identify residual tumor in a patient with cyclic CS. In this case presentation, we will highlight the utility of the DesST to establish both partial and successful tumor resection in such a patient.

Case Presentation

A 26-year-old woman developed irregular menses, hair loss, facial rounding, a dorsocervical fat pad, and wide violaceous abdominal striae, accompanied by an unexplained 30-pound weight gain over 3 months. Over the same period, she also noted worsening of longstanding fatigue, anxiety, depression, and acne. Eventually, 1 year after these symptoms started, she was diagnosed with CS based on elevated midnight serum cortisol (24.5 µg/dL [SI: 675 nmol/L], reference range [RR]: <7.5 µg/dL [<207 nmol/L]), 24-hour urine free cortisol (UFC) (337 µg/day [SI: 931 nmol/day], RR: 3.5-45 µg/day [SI: 9.7-124 nmol/day]), and failure to suppress serum cortisol during a 48-hour low-dose dexamethasone suppression test (48-hour cortisol: 26.7 µg/dL [SI: 736 nmol/L], RR: <1.8 µg/dL [SI: <50 nmol/L]). ACTH was not suppressed and pituitary magnetic resonance imaging (MRI) revealed a right-sided 7 mm microadenoma. Bilateral inferior petrosal sinus sampling showed a high central-to-peripheral ACTH ratio, indicative of CD.

Because of surgical delays related to the COVID-19 pandemic, she was started on a block-and-replace regimen of metyrapone and hydrocortisone (HC) before undergoing TSS 6 months later, removing a tumor located in the right superior posterior portion of the pituitary. Pathology confirmed a pituitary tumor with diffuse positivity for ACTH, rare positivity for GH and prolactin, and low mitotic activity (Ki67 index <3%). Morning serum cortisol dropped to 1.2 µg/dL (SI: 33 nmol/L) (RR: 3.7-19.4 µg/dL [SI: 102-535 nmol/L]) on postoperative day 4, at which point physiologic HC replacement was started. HC was eventually tapered and stopped 8 months later, when morning serum cortisol had recovered. Postoperatively, her acne and menstrual irregularities resolved while hair loss continued and her weight stabilized without any significant reduction.

Later, she again developed worsening anxiety and a severely depressed mood to the point where she could barely function at her job. Because of these worsening symptoms, repeat testing was performed 10 months after surgery, confirming return of hypercortisolism: midnight serum cortisol 20.5 µg/dL (SI: 565 nmol/L), UFC 82 µg/day (SI: 227 nmol/day). A small lesion was seen on pituitary MRI, thought to represent postoperative changes or a residual adenoma.

Diagnostic Assessment

The patient presented to our institution for a second opinion. A pituitary MRI was unchanged from the month prior. Unexpectedly, laboratory values now showed undetectable bedtime salivary (<50 ng/dL [SI: 1.4 nmol/L], RR: <100 ng/dL [SI: <2.8 nmol/L]) and morning serum cortisol (<1 µg/dL [SI: <27.6 nmol/L]), and low-normal ACTH (11.9 pg/mL [SI: 2.6 pmol/L], RR: 5.0-46.0 pg/mL [SI: 1.1-10.1 pmol/L]), and UFC (5.6 µg/day [SI: 15.5 nmol/day]). She did not have clinical symptoms of adrenal insufficiency. These results, indicative of secondary adrenal insufficiency, were in stark contrast to the hypercortisolism confirmed 1 month earlier, raising suspicion for apoplexy of residual tumor tissue or cyclic CS. Upon further questioning, the patient reported previous waxing and waning of acne severity, but no clear cyclicity of other symptoms. She felt that it was not possible for her to assess emotional or cognitive variability apart from that caused by the COVID-19 pandemic. Three weeks later, she underwent a DesST, during which baseline cortisol and ACTH were 3.1 µg/dL (SI: 86 nmol/L) and 34.1 pg/mL (SI: 7.5 pmol/L), respectively. After desmopressin, ACTH increased +111% at +15/30 minutes and cortisol increased +172% at +30/45 minutes (Fig. 1). This positive response was interpreted as confirming the presence of residual tumor tissue.

ACTH and cortisol responses during the desmopressin stimulation test (DesST) before and after the patient's second transsphenoidal surgery. Plasma ACTH (A) and serum cortisol (B) levels were measured twice at baseline before and 15, 30, 45, and 60 minutes after intravenous administration of 10 µg desmopressin. Circles and squares represent the values from tests performed before and after surgery, respectively. The presence of a response (despite a low baseline cortisol level) in the preoperative test was considered to represent residual corticotroph tumor tissue; the postoperative loss of response to desmopressin was thought to represent successful resection of residual tumor.

Figure 1.

ACTH and cortisol responses during the desmopressin stimulation test (DesST) before and after the patient’s second transsphenoidal surgery. Plasma ACTH (A) and serum cortisol (B) levels were measured twice at baseline before and 15, 30, 45, and 60 minutes after intravenous administration of 10 µg desmopressin. Circles and squares represent the values from tests performed before and after surgery, respectively. The presence of a response (despite a low baseline cortisol level) in the preoperative test was considered to represent residual corticotroph tumor tissue; the postoperative loss of response to desmopressin was thought to represent successful resection of residual tumor.

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Treatment

Two weeks after the positive DesST, on admission for repeat TSS, morning serum cortisol had risen to 15.2 µg/dL (SI: 419 nmol/L). After resection of residual tissue within the anteroinferior and right lateral aspect of the gland, pathology again confirmed a focus of ACTH-positive tumor. By postoperative day 3, morning serum cortisol was again undetectable with an unchanged plasma ACTH of 12.1 pg/mL (SI: 2.7 pmol/L). Because of the difficulty in distinguishing a satisfactory postoperative biochemical response from a period of low disease activity in cyclic CS, a second DesST was performed. This time the test was negative, with ACTH increasing by only 8%, whereas cortisol remained undetectable throughout (Fig. 1). This drastic change in response to desmopressin was believed to represent successful resection of residual tumor tissue. She was discharged on physiologic HC replacement and daily desmopressin after developing postoperative AVP deficiency.

Outcome and Follow-up

The AVP deficiency resolved over 6 months, whereas HC was stopped after 8 months, following a normal insulin tolerance test. The patient lost 20 pounds in the first 9 months after her second surgery, before gradually losing an additional 40 pounds over the following 3 years, reaching her baseline weight. The facial rounding and dorsocervical fat pad resolved, and acne improved. Three years after her second surgery, biochemical remission was maintained but she continued to experience hair loss, reduced taste and smell, and fluctuating severity of her preexisting fatigue, anxiety, and depression.

Discussion

Of note, our patient’s initial evaluation and surgery took place at an expert pituitary center in the United Kingdom, whereas the second evaluation was performed in the United States. This case shows some regional differences in testing protocols; for example, the 48-hour dexamethasone suppression and insulin tolerance tests are used more often in the United Kingdom. However, both surgical procedures were performed by high-volume pituitary surgeons, which is crucial to maximize the probability of remission [2].

While previous reports have described the role of the DesST in CD diagnosis [9], our case highlights its unique utility during periods of low disease activity in cyclic CD. Other tests for the diagnosis or etiology of CS rely on ongoing disease activity and require ongoing tumoral secretion of ACTH accompanied by suppression of healthy corticotrophs. Importantly, most healthy corticotrophs do not exhibit a significant response to desmopressin [7, 9]. In our patient, the diagnosis of CD was confirmed based on previous surgical pathology. Although documented recurrent hypercortisolism and CS symptoms were highly suspicious, the presence of residual disease was questioned due to the lack of ongoing hypercortisolism. In this context, the clearly positive response to DesST provided supportive evidence for pursuing a second TSS. The subsequent postoperative loss of response to desmopressin was interpreted as representing successful resection of all residual tumor tissue, which was supported by enduring remission of most symptoms 3 years after surgery. Biochemical postoperative assessments are based on trends in ACTH and cortisol. Typically, both hormones plummet after successful removal of an ACTH-producing tumor, since healthy corticotrophs remain suppressed because of longstanding hypercortisolism. Corticotrophs take at least 6 months to recover; earlier normalization of ACTH and cortisol raises concern for residual tumor tissue [12].

Postoperative hormonal trends may be different in 2 settings that were both relevant to our patient: preoperative medical therapy to restore eucortisolism and cyclic CS. In both scenarios, recent hypercortisolism may have been mild or absent, potentially allowing for a swift recovery of healthy corticotrophs. Postoperative ACTH and cortisol levels may be normal, making it difficult to establish a biochemical cure. In this setting, the usual screening tests for hypercortisolism (UFC, bedtime cortisol, low-dose dexamethasone suppression test) are useful to determine whether excessive ACTH secretion persists.

However, these postoperative screening tests for hypercortisolism may not be reliable in cyclic CS since low or normal ACTH and cortisol levels can reflect either remission or low disease activity. The DesST may be particularly useful in this situation to identify residual disease or confirm successful tumor resection. For this test to be useful, however, it is important to obtain a preoperative DesST to establish a baseline because a minority of tumors causing CD do not respond to desmopressin [9].

Learning Points

  • Most healthy pituitary corticotrophs and tumors causing ectopic ACTH syndrome do not exhibit a response during the desmopressin stimulation test (DesST), making it useful for Cushing disease (CD) diagnosis.

  • The DesST may be particularly useful during periods of low disease activity in cyclic Cushing syndrome, as other dynamic tests used to diagnose CD may be uninterpretable in this setting.

  • Postoperatively, the DesST may be useful to confirm successful tumor resection and to monitor for CD recurrence. It is, however, important to obtain a preoperative DesST to establish whether the causative tumor is responsive to desmopressin.

Contributors

All authors made individual contributions to authorship. B.M.B., L.K.N., and H.E. were involved in the writing and submission of the manuscript. W.D., R.M., L.K.N., and H.E. were involved in the diagnosis and management of this patient. All authors reviewed and approved the final draft.

Funding

This research was supported by the Intramural Research Program of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) within the National Institutes of Health (NIH). The contributions of the NIH authors were made as part of their official duties as NIH federal employees, are in compliance with agency policy requirements, and are considered Works of the United States Government. However, the findings and conclusions presented in this paper are those of the authors and do not necessarily reflect the views of the NIH or the U.S. Department of Health and Human Services.

Disclosures

B.M.B., W.D., R.M., and H.E. have nothing to disclose. L.K.N. receives royalties from UpToDate.

Informed Patient Consent for Publication

Signed informed consent obtained directly from the patient.

Published by Oxford University Press on behalf of the Endocrine Society 2025.
This work is written by (a) US Government employee(s) and is in the public domain in the US. 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.

Filed under: Cushing's, pituitary, Rare Diseases, Treatments | Tagged: , , , , | Leave a comment »

Sleep Disturbances in Patients With Cushing Syndrome and Mild Autonomous Cortisol Secretion

Posted on October 16, 2025 by MaryO

The Journal of Clinical Endocrinology & Metabolism, dgaf553, https://doi.org/10.1210/clinem/dgaf553

Abstract

Context

The impact of active hypercortisolism on sleep is incompletely characterized. Studies report impaired sleep in patients with Cushing syndrome (CS). Patients with mild autonomous cortisol secretion (MACS) demonstrate mild nocturnal hypercortisolism that could impact sleep.

Objectives

To characterize sleep abnormalities in patients with CS and MACS using the Pittsburgh Sleep Quality Index (PSQI), identify factors associated with poor sleep, and compare sleep abnormalities in patients with MACS versus referent subjects.

Methods

We conducted a single-center cross-sectional study of adults with active CS and MACS. Clinical and biochemical severity scores for hypercortisolism were calculated. Parallelly, we enrolled referent subjects. Quality of life was assessed using 1) Short Form-36 in all participants, and 2) Cushing QoL in patients with active hypercortisolism. Sleep quality was assessed using PSQI.

Results

PSQI was assessed in 154 patients with CS (mean 12, SD ±4.5), 194 patients with MACS (mean 11, SD 4.6), and 89 referents (mean 5, SD ±3.4). Patients with MACS exhibited shorter sleep duration, longer sleep latency, more severe daytime dysfunction, lower sleep efficiency, and a higher sleep medication use compared to referent subjects (P = <0.001 for all). Age-, sex, and BMI adjusted analysis demonstrated no differences in PSQI or its subcomponents between patients with CS and MACS (P >0.05 for all). In a multivariable analysis of patients with MACS, younger age, female sex and higher clinical hypercortisolism severity score were associated with impaired sleep. In patients with CS, only younger age was associated with poor sleep.

Conclusions

Patients with MACS demonstrate sleep impairment that is similar to patients with CS. Younger women with higher clinical severity of MACS are more likely to have impaired sleep.

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Global Longitudinal Strain Reduction With Apical Sparing in Cushing Syndrome-Related Heart Failure With Preserved Ejection Fraction (HFpEF)

Posted on October 6, 2025 by MaryO

We describe a case of a 56-year-old woman with a history of recurrent pituitary adenoma, not well followed, and known comorbidities of coronary artery disease, hypertension, and type 2 diabetes mellitus. She arrived with severely high blood pressure and signs pointing to hypercortisolism.

Further evaluation revealed left ventricular hypertrophy, reduced global longitudinal strain, and preserved left ventricular ejection fraction, consistent with heart failure with preserved ejection fraction (HFpEF). Workup for amyloidosis was negative.

This case highlights that chronic hypercortisolism may cause pathophysiological changes in the heart, leading to HFpEF, and may induce myocardial fibrosis and impaired myocardial mechanics, producing an echocardiographic pattern that can mimic infiltrative cardiomyopathy. Recognition of this overlap is crucial to avoid misdiagnosis and to ensure timely endocrine and cardiovascular management.

Read here.

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Altered Microbiome Signature in Cushing’s Syndrome Persists Beyond Remission

Posted on September 27, 2025 by MaryO

German Rubinstein, Ilias Lagkouvardos, Evangelia Intze, Andrea Osswald, Stephanie Zopp, Leah Theresa Braun, Adriana Albani, Heike Künzel, Anna Riester, Felix Beuschlein, Martin Reincke, Katrin Ritzel
The Journal of Clinical Endocrinology & Metabolism, Volume 110, Issue 9, September 2025, Pages 2615–2622
https://doi.org/10.1210/clinem/dgae887

Abstract

Context

Patients with Cushing’s syndrome (CS) suffer from metabolic and cardiovascular comorbidities caused by hypercortisolism. The human gut microbiome responds to different pathological conditions.

Objective

The aim of our study was to analyze the effect of chronic endogenous cortisol excess on the gut microbiome.

Methods

We prospectively recruited 18 patients with endogenous CS of different etiologies (mainly pituitary CS, n = 13). Patients provided a stool sample during active CS and 1 to 2 years after successful surgical treatment being in biochemical remission. In addition, 36 patients, in whom CS was excluded, served as an obese control group and 108 samples from healthy lean students were used as a reference group. Amplicons of the V3/V4 region of the 16S ribosomal RNA gene, from every sample, were sequenced and clustered into operational taxonomic units. The microbial profiles of CS patients were then compared to the control and reference groups using R scripts.

Results

In comparison to lean references, the gut microbiome of patients with florid CS demonstrated a disturbed microbial profile. Microbial dysbiosis of patients with CS was maintained even after biochemical remission following curative surgery.

Conclusion

Patients with CS have a distinct and disturbed gut microbiome that persists even after surgery, indicating a possible target for additional probiotic interventions to accelerate convergence to a healthy microbiome.

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