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Diagnosis and Differential Diagnosis of Cushing’s Syndrome

Posted on April 8, 2026 by MaryO

D. Lynn Loriaux, M.D., Ph.D.

N Engl J Med 2017; 376:1451-1459April 13, 2017DOI: 10.1056/NEJMra1505550

More than a century ago, Harvey Cushing introduced the term “pluriglandular syndrome” to describe a disorder characterized by rapid development of central obesity, arterial hypertension, proximal muscle weakness, diabetes mellitus, oligomenorrhea, hirsutism, thin skin, and ecchymoses.1 Cushing knew that this syndrome was associated with adrenal cancer,2 and he suspected that some cases might have a pituitary component.

On September 6, 1911, he performed a craniotomy on one of his patients (referred to as Case XLV) but found no pituitary tumor.3 In his description of the case, he goes on to say that “we may perchance be on the way toward the recognition of the consequences of hyperadrenalism.”2 With time, it became clear that the disorder could be caused by small basophilic adenomas of the pituitary gland,4 and the pluriglandular syndrome became known as Cushing’s syndrome.

Fuller Albright provided the next conceptual advance in an extraordinary report, published in the first volume of the Laurentian Hormone Conference, “The Effects of Hormones on Osteogenesis in Man”5:

It has been our concept that protoplasm in general, like the protoplasmic matrix of bone, is constantly being anabolized and catabolized at one and the same time; a factor which increases catabolism would lead to very much the same net result as a factor which inhibits anabolism, but there would be some differences; it is my belief that the “S” hormone [cortisol] is anti-anabolic rather than catabolic. . . . The anti-anabolism . . . is contrasted with the increased anabolism due to an excess of the “N” hormone [testosterone] in the adreno-genital syndrome. This anti-anabolism of protoplasm in Cushing’s syndrome accounts for not only the osteoporosis, but the muscular weakness, the thin skin, probably the easy bruisability, and possibly the atrophy of the lymphoid tissues and thymus.

Nonetheless, in the intervening years, the physical examination of patients suspected to have glucocorticoid excess focused on the anabolic changes, essentially to the exclusion of the antianabolic changes. With the rapid increase in the rate of obesity in the general population, Cushing’s syndrome can no longer be reliably separated from the metabolic syndrome of simple obesity on the basis of anabolic signs alone. However, the antianabolic changes in Cushing’s syndrome are very effective in making this distinction. This review focuses on the problems introduced into the diagnosis and differential diagnosis of Cushing’s syndrome by the obesity epidemic and on ways to alter the traditional approach, using the antianabolic changes of excess cortisol to separate patients with Cushing’s syndrome from obese patients with the insulin-resistant metabolic syndrome.

PHYSICAL EXAMINATION

Andreas Vesalius (1514–1564) published his transformational work on human anatomy, De Humani Corporis Fabrica Libri Septem, in 1543. It is the book that corrected many of Galen’s anatomical errors. The book was met with considerable hostility. As an example, Jacobus Sylvius (Jacques Dubois, 1478–1555), the world’s leading anatomist at the time and Vesalius’s former mentor, on being asked his opinion of the work, replied, “Galen is not wrong. It is man that has changed, and not for the better.”6 This was not true then, but it is true now.

Approximately one third of the U.S. population is obese. The worldwide prevalence of the metabolic syndrome among obese persons is conservatively estimated at 10%; that is, approximately 12 million people have the obesity-related metabolic syndrome.7,8 The clinical picture of this syndrome is almost the same as that of Cushing’s syndrome.9,10 The prevalence of undiagnosed Cushing’s syndrome is about 75 cases per 1 million population, or 24,000 affected persons. On the basis of these prevalence estimates, the chance that a person with obesity, hypertension, hirsutism, type 2 diabetes, and dyslipidemia has Cushing’s syndrome is about 1 in 500. In Harvey Cushing’s era, when obesity was rare, making the diagnosis of Cushing’s syndrome was the most certain aspect of the management of this disorder. Today, making the diagnosis is the least certain aspect in the care of patients with Cushing’s syndrome.

The metabolic syndrome caused by glucocorticoid hypersecretion can be differentiated from the obesity-associated metabolic syndrome with the use of a careful assessment of Albright’s antianabolic effects of cortisol. These effects — osteopenia, thin skin, and ecchymoses — are present in patients with Cushing’s syndrome but not in patients with simple obesity.

Patients in whom osteoporosis is diagnosed radiographically are more likely to have Cushing’s syndrome than those who do not have osteoporosis, with a positive likelihood ratio of 11.11-13 Today, a z score of −2 at the lumbar spine supports this criterion. Skinfold thickness is conveniently measured with an electrocardiographic caliper that has the points dulled with a sharpening stone and the screws tightened so that the gap is maintained when the caliper is removed from the skinfold. The skin over the proximal phalanx of the middle finger of the nondominant hand is commonly used for this measurement

(Figure 1 FIGURE 1Measurement of Skinfold Thickness.). A thickness of less than 2 mm is considered to be thin skin. Patients who have thin skin are more likely to have Cushing’s syndrome, with a positive likelihood ratio of 116

(Figure 2 FIGURE 2 Comparison of Skinfold Thickness in Patients with Cushing’s Syndrome and Those with Other Conditions Related to Insulin Resistance.).13-15 Finally, patients who have three or more ecchymoses that are larger than 1 cm in diameter and not associated with trauma such as venipuncture are more likely to have Cushing’s syndrome than are patients without such findings, with a positive likelihood ratio of 4.13,16

If we know the prevalence of undiagnosed Cushing’s syndrome in the population of persons with the obesity-related metabolic syndrome, we can begin to calculate the probability that a person has Cushing’s syndrome, using the likelihood ratios for the antianabolic features observed on physical examination. Likelihood ratios can be converted into probabilities with the use of Bayes’ theorem. This conversion is markedly facilitated by the Fagan nomogram for this purpose.17

The prevalence of undiagnosed Cushing’s syndrome is not known, but it can be estimated. Two persons per 1 million population die from adrenal cancer every year.18 The current life span for patients with adrenocortical carcinoma, after diagnosis, is between 2 and 4 years.19,20 Allowing 3 years to make the diagnosis, the prevalence of undiagnosed Cushing’s syndrome is 6 cases per million. In most case series of Cushing’s syndrome, an average of 8% of patients have adrenal carcinoma.21 If 6 per million is 8% of the group, the total Cushing’s syndrome group is 75 persons per million, or 24,000 persons. If all 24,000 patients are included in the metabolic syndrome group, comprising 12 million people, the prevalence of Cushing’s syndrome is 0.002, or 0.2%. With a probability of 0.2% and a likelihood ratio of 116 for thin skin, 18 for osteopenia, and 4 for ecchymoses, the probability that a patient with these three findings has Cushing’s syndrome is 95%.

URINARY FREE CORTISOL

The diagnosis of all endocrine diseases requires a clinical presentation that is compatible with the disease, as well as identification of the pathophysiological cause. An assessment for excess glucocorticoid effects can be made by measuring the 24-hour urinary free cortisol level.22 There are two kinds of free cortisol: plasma protein-unbound cortisol and cortisol unconjugated to sulfuric or hyaluronic acid. Protein-unbound cortisol is filtered in the glomerulus and then reabsorbed in the collecting system. About 3% of filtered cortisol ends up in the urine. This free cortisol in the urine is unconjugated. Thus, the urinary free cortisol level is a direct reflection of the free, bioactive cortisol level in plasma. The free cortisol level is quantified in a 24-hour urine sample by averaging the increased secretion of cortisol in the morning and the decreased secretion in the afternoon and at night. Urinary creatinine is also measured to determine whether the collection is complete. Creatinine levels of less than 1.5 g per day for men and less than 1 g per day for women indicate incomplete collection, and the test should be repeated in patients with these levels.

Unconjugated cortisol can be extracted directly from urine with a nonpolar lipid solvent. After extraction, the cortisol is purified by means of high-pressure liquid chromatography and then quantified with a binding assay, usually radioimmunoassay. Free cortisol also can be quantitated directly by means of mass spectroscopy. The urinary free cortisol assay of choice uses high-pressure liquid chromatographic separation followed by mass spectrometric quantitation.23 With the use of this assay, the urinary free cortisol level in healthy adults ranges from 8 to 51 μg per 24 hours (mean [±SD], 23±8). Clinical depression increases urinary free cortisol excretion, and most studies show that the level of urinary free cortisol ranges from 10 to 60 μg per day in patients with typical clinical signs and symptoms of depression. If we use 60 μg per day as the cutoff between normal values (<60 μg per day) and elevated values (≥60 μg per day), urinary free cortisol excretion of 62 μg per day or more has a positive likelihood ratio of 11.24 Thus, in a patient presenting with obesity, hypertension, type 2 diabetes, and hirsutism who has thin skin, osteopenia, ecchymoses, and an elevated urinary free cortisol level, the probability of Cushing’s syndrome is 1 (100%). For such patients, the clinician should move directly to a differential diagnostic evaluation.

DEXAMETHASONE-SUPPRESSION TEST

The dexamethasone-suppression test is commonly used in the diagnosis of Cushing’s syndrome. This test was developed by Grant Liddle in the early 1960s as a differential diagnostic test to separate corticotropin-dependent from corticotropin-independent Cushing’s syndrome. This is now done by measuring the plasma corticotropin level. Unfortunately, dexamethasone suppression has continued to be used as a screening test for Cushing’s syndrome.

The control group for this test comprises patients with obesity and depression in whom cortisol secretion is not suppressed in response to an oral dose of 1 mg of dexamethasone at midnight. Of the current U.S. population of 360 million people, approximately one third (120 million people) are obese. Of those who are obese, 10% (12 million people) have depression. In half these patients (6 million people), the plasma cortisol level will not be suppressed in response to a dexamethasone challenge. On the basis of my estimate of the current prevalence of undiagnosed Cushing’s syndrome (24,000 cases) and the estimate of the at-risk population (6 million persons), the positive predictive value of the dexamethasone-suppression test is only 0.4%. Thus, this test should not influence what the physician does next and should no longer be used for this purpose.

OUTLIERS

For patients with convincing evidence of Cushing’s syndrome on physical examination and an elevated 24-hour urinary free cortisol level, the differential diagnostic process outlined below should be initiated. However, a small group of patients will not meet these criteria.

Some patients have a strongly positive physical examination but low or zero urinary free cortisol excretion. Plasma corticotropin levels are suppressed in these patients. These patients are receiving exogenous glucocorticoids. The glucocorticoid must be identified, and a plan must be made for its discontinuation. Sometimes the glucocorticoid is being given by proxy (e.g., by a parent to a child), and no history of glucocorticoid administration can be found. Nevertheless, the glucocorticoid must be identified and discontinued.

Other patients have few or no clinical signs of Cushing’s syndrome but do have elevated urinary free cortisol excretion. Plasma corticotropin is measurable in these patients. They are usually identified during an evaluation for arterial hypertension. All such patients should undergo inferior petrosal sinus sampling to determine the source of corticotropin secretion. Ectopic sources are almost always neoplastic and are usually in the chest.25 Patients with eutopic secretion usually have the syndrome of generalized glucocorticoid resistance.26

Finally, a few patients have convincing findings on physical examination coupled with a normal urinary free cortisol level. In such cases, the clinician should make sure that urinary free cortisol is being measured with high-performance liquid chromatography and mass spectrometry, that renal function is normal, and that the collections are complete. “Periodic” Cushing’s syndrome must be ruled out by measuring urinary free cortisol frequently over the course of a month.27 If these efforts fail, the patient should be followed for a year, with urinary free cortisol measurements performed frequently. No additional tests should be performed until the situation is sorted out. More tests would be likely to lead to an unnecessary surgical procedure.

DIFFERENTIAL DIAGNOSIS

The differential diagnosis of Cushing’s syndrome is shown in Figure 3

FIGURE 3Differential Diagnosis of Cushing’s Syndrome.. If plasma corticotropin is measurable, the disease process is corticotropin-dependent. If corticotropin is not measurable, the process is corticotropin-independent.

Corticotropin-dependent causes of Cushing’s syndrome are divided into those in which the corticotropin comes from the pituitary (eutopic causes) and those in which the corticotropin comes from elsewhere (ectopic causes). This differentiation is made with the measurement of corticotropin in inferior petrosal sinus plasma and the simultaneous measurement of corticotropin in peripheral (antecubital) plasma immediately after corticotropin-releasing hormone stimulation of pituitary corticotropin secretion. In samples obtained 4, 6, and 15 minutes after stimulation with corticotropin-releasing hormone, eutopic corticotropin secretion is associated with a ratio of the central-plasma corticotropin level to the peripheral-plasma corticotropin level of 3 or more. Ectopic corticotropin secretion is associated with a central-to-peripheral corticotropin ratio of less than 3. The positive predictive value of this test is 1 (Figure 4

FIGURE 4Maximal Ratio of Corticotropin in Inferior Petrosal Sinus Plasma to Corticotropin in Peripheral Plasma in Patients with Cushing’s Syndrome, Ectopic Corticotropin Secretion, or Adrenal Disease.).28

Although some authorities suggest that inferior petrosal sinus sampling can safely be bypassed in patients with corticotropin-dependent Cushing’s syndrome and a well-defined pituitary adenoma, I disagree. The incidence of nonfunctioning pituitary microadenomas is between 15% and 40%.29 This means that up to 40% of patients with ectopic secretion of corticotropin have an incidental pituitary abnormality. If it is assumed that the pituitary abnormality is responsible for corticotropin secretion, 15 to 40% of patients with ectopic secretion of corticotropin will be misdiagnosed and submitted to a transsphenoidal exploration of the sella turcica and pituitary gland. The prevalence of ectopic corticotropin secretion in the population of patients with undiagnosed Cushing’s syndrome is about 10%, accounting for 2400 patients. Up to 40% of these patients, or 960, have an incidental pituitary tumor. The mortality associated with transsphenoidal microadenomectomy is 1%.30 If all 360 to 960 patients undergo this procedure, there will be up to 10 deaths from an operation that can have no benefit. For this reason alone, all patients with corticotropin-dependent Cushing’s syndrome should undergo inferior petrosal sinus sampling to confirm the source of corticotropin secretion before any surgical intervention is contemplated.

Patients with eutopic corticotropin secretion are almost certain to have a corticotropin-secreting pituitary microadenoma. An occasional patient will have alcohol-induced pseudo–Cushing’s syndrome. The slightest suggestion of alcoholism should lead to a 3-week abstinence period before any surgery is considered.31

Patients with ectopic corticotropin secretion are first evaluated with computed tomography (CT) or magnetic resonance imaging (MRI) of the chest. In two thirds of these patients, a tumor will be found.25 If nothing is found in the chest, MRI of the abdominal and pelvic organs is performed. If these additional imaging studies are also negative, there are two options: bilateral adrenalectomy or blockade of cortisol synthesis. If blockade is chosen, the patient should undergo repeat scanning at 6-month intervals.32 If no source is found by the end of the second year, it is unlikely that the source will ever be found, and bilateral adrenalectomy should be performed for definitive treatment (Doppman JL: personal communication).

Corticotropin-independent Cushing’s syndrome is usually caused by an adrenal neoplasm. Benign tumors tend to be small (<5 cm in diameter) and secrete a single hormone, cortisol. The contralateral adrenal gland is suppressed by the cortisol secreted from the tumorous gland. If the value for Hounsfield units is less than 10 and the washout of contrast material is greater than 60% at 15 minutes, the tumor is almost certainly benign.33 Such tumors can be treated successfully with laparoscopic adrenalectomy.

The syndromes of micronodular and macronodular adrenal dysplasia usually affect both adrenal glands. The nodules secrete cortisol. Corticotropin is suppressed, as is the internodular tissue of the adrenal glands. Percutaneous bilateral adrenalectomy, followed by glucocorticoid and mineralocorticoid treatment, is curative.

Adrenal tumors secreting more than one hormone (i.e., cortisol and androgen or estrogen) are almost always malignant. Surgical removal of all detectable disease is indicated, as is a careful search for metastases. If metastases are found, they should be removed. This usually requires an open adrenalectomy. It goes without saying that adrenal tumors, nodules, and metastases should be treated by the most experienced endocrine cancer surgeon available.

If the plasma cortisol level on the morning after a transsphenoidal microadenomectomy is 0, the operation was a success. The patient should be treated with oral hydrocortisone, at a dose of 12 mg per square meter of body-surface area once a day in the morning, and a tetracosactide (Cortrosyn) stimulation test should be performed at 3-month intervals. When the tetracosactide-stimulated plasma cortisol level is higher than 20 μg per deciliter (551 μmol per liter), cortisol administration can be stopped. The same rule applies in the case of a unilateral adrenalectomy. If the adrenalectomy is bilateral, cortisol, at a dose of 12 to 15 mg per square meter per day, and fludrocortisone (Florinef), at a dose of 100 μg per day, should be prescribed as lifelong therapy.

SUMMARY

The obesity epidemic has led to necessary changes in the evaluation and treatment of patients with Cushing’s syndrome. The most dramatic change is the emphasis on the antianabolic alterations in Cushing’s syndrome, which can provide a strong basis for separating patients with Cushing’s syndrome from the more numerous patients with obesity and the metabolic syndrome. More can be done along these lines. Likelihood ratios are known for proximal muscle weakness and can be known for brain atrophy and growth failure in children.

The dexamethasone-suppression test, although still very popular, no longer has a role in the evaluation and treatment of patients with Cushing’s syndrome. Only three biochemical tests are needed: urinary free cortisol, plasma corticotropin, and plasma cortisol measurements. Urinary free cortisol excretion is the test that confirms the clinical diagnosis of Cushing’s syndrome. To be trustworthy, it must be performed in the most stringent way, with the use of high-pressure liquid chromatography followed by mass spectrometric quantitation of cortisol. Measurement of plasma corticotropin is used to separate corticotropin-dependent from corticotropin-independent causes of Cushing’s syndrome and to separate eutopic from ectopic secretion of corticotropin. Inferior petrosal sinus sampling should be performed in all patients with corticotropin-dependent Cushing’s syndrome because of the high prevalence of nonfunctioning incidental pituitary adenomas among such patients. Measurement of plasma cortisol has only one use: determining the success or failure of transsphenoidal microadenomectomy or adrenalectomy. If the plasma cortisol level is not measurable on the morning after the operation (<5 μg per deciliter [138 μmol per liter]), the procedure was a success; if it is measurable, the operation failed. The surgeon must not administer intraoperative or postoperative synthetic glucocorticoids until the plasma cortisol level has been measured.

Successful evaluation of a patient who is suspected of having Cushing’s syndrome requires an endocrinologist who is skilled in physical diagnosis. Also required is a laboratory that measures urinary free cortisol using high-performance liquid chromatography and mass spectrometry and that can measure plasma cortisol and plasma corticotropin by means of radioimmunoassay.

Inferior petrosal sinus sampling is performed by an interventional radiologist. The treatment for all causes of Cushing’s syndrome, other than exogenous glucocorticoids, is surgical, and neurosurgeons, endocrine surgeons, and cancer surgeons are needed. This level of multidisciplinary medical expertise is usually found only at academic medical centers. Thus, most, if not all, patients with Cushing’s syndrome should be referred to such a center for treatment.

Disclosure forms provided by the author are available with the full text of this article at NEJM.org.

No potential conflict of interest relevant to this article was reported.

SOURCE INFORMATION

From the Division of Endocrinology, Diabetes, and Clinical Nutrition, Oregon Health and Science University, Portland.

Address reprint requests to Dr. Loriaux at the Division of Endocrinology, Diabetes, and Clinical Nutrition, Oregon Health and Science University, 3181 SW Sam Jackson Park Rd., L607, Portland, OR 97239-3098, or at loriauxl@ohsu.edu.

From http://www.nejm.org/doi/full/10.1056/NEJMra1505550

Filed under: adrenal, Cushing, Cushing's, Helpful Doctors, pituitary | Tagged: 24-hour urinary free cortisol, adenoma, adrenal, central obesity, craniotomy, dexamethasone suppression test, diabetes mellitus, Dr. Harvey Cushing, Dr. Lynn Loriaux, ecchymoses, hirsutism, hypertension, Inferior petrosal sinus sampling, IPSS, luriglandular syndrome, muscle weakness, OHSU, oligomenorrhea, Oregon Health & Science University, pituitary, thin skin, UFC | Leave a comment »

Inferior Petrosal Sinus Sampling (IPSS) Tumor Lateralization and The Surgical Treatment of Cushing’s Disease

Posted on December 22, 2025 by MaryO

ABSTRACT

Objective

To determine whether accurate inferior petrosal sinus sampling (IPSS) tumor lateralization is associated with improved clinical outcomes following the surgical treatment of Cushing’s disease.

Methods

The presented study was performed in accordance with PRISMA guidelines. Data regarding patient demographics, IPSS tumor lateralization, and postoperative endocrinologic outcomes were abstracted and pooled with random effects meta-analysis models. Additional meta-regression models were used to examine the association between the accuracy of IPSS tumor lateralization and postoperative outcomes (recurrence/persistence or remission/cure). Statistical analyses were performed using the Comprehensive Meta-Analysis software (significance of P<0.05).

Results

Seventeen eligible articles were identified, yielding data on 461 patients. Within average follow-up duration (∼59 months), the rate of correct IPSS tumor lateralization was 69% [95% Confidence Interval: 61%, 76%], and the rate of postoperative remission/cure was 78% [67%, 86%]. Preoperative IPSS tumor lateralization was concordant with MRI lateralization for 53% of patients [40%, 66%]. There was no significant association between the rate of correct IPSS tumor lateralization and postoperative remission/cure among study-level data (P=0.735). Additionally, there was no association among subgroup analyses for studies using stimulatory agents during IPSS (corticotropin-releasing hormone or desmopressin, P=0.635), nor among subgroup analyses for adult (P=0.363) and pediatric (P=0.931) patients.

Conclusions

Limited data suggest that the rate of correct IPSS tumor lateralization may not be positively associated with postoperative remission or cure in patients with Cushing’s disease. These findings bring into question the utility of IPSS tumor lateralization in the context of preoperative planning and surgical approach rather than confirming a pituitary source.

From https://www.sciencedirect.com/science/article/abs/pii/S187887502301745X

Filed under: Cushing's, Diagnostic Testing, pituitary | Tagged: Cushing's, Inferior petrosal sinus sampling, IPSS, pituitary | Leave a comment »

Consecutive Resections of Double Pituitary Adenoma for Resolution of Cushing Disease

Posted on December 20, 2025 by MaryO

BACKGROUND

Double pituitary adenomas are rare presentations of two distinct adenohypophyseal lesions seen in <1% of surgical cases. Increased rates of recurrence or persistence are reported in the resection of Cushing microadenomas and are attributed to the small tumor size and localization difficulties. The authors report a case of surgical treatment failure of Cushing disease because of the presence of a secondary pituitary adenoma.

OBSERVATIONS

A 32-year-old woman with a history of prolactin excess and pituitary lesion presented with oligomenorrhea, weight gain, facial fullness, and hirsutism. Urinary and nighttime salivary cortisol elevation were elevated. Magnetic resonance imaging confirmed a 4-mm³ pituitary lesion. Inferior petrosal sinus sampling was diagnostic for Cushing disease. Primary endoscopic endonasal transsphenoidal resection was performed to remove what was determined to be a lactotroph-secreting tumor on immunohistochemistry with persistent hypercortisolism. Repeat resection yielded a corticotroph-secreting tumor and postoperative hypoadrenalism followed by long-term normalization of the hypothalamic-pituitary-adrenal axis.

LESSONS

This case demonstrates the importance of multidisciplinary management and postoperative hormonal follow-up in patients with Cushing disease. Improved strategies for localization of the active tumor in double pituitary adenomas are essential for primary surgical success and resolution of endocrinopathies.

Keywords:: pituitary neuroendocrine tumor; PitNET; pituitary adenoma; Cushing disease; prolactinoma; transsphenoidal

ABBREVIATIONS

ACTH = adrenocorticotrophic hormone; BMI = body mass index; DHEA-S = dehydroepiandrosterone sulfate; FSH = follicle-stimulating hormone; GH = growth hormone; IHC = immunohistochemical; IPSS = inferior petrosal sinus sampling; LH = luteinizing hormone; MRI = magnetic resonance imaging; POD = postoperative day; T4 = thyroxine; TF = transcription factor; TSH = thyroid-stimulating hormone; UFC = urinary free cortisol

Pituitary adenomas are adenohypophyseal tumors that can cause endocrinopathies, such as pituitary hormone hypersecretion or anterior hypopituitarism. Cell lineages are used to classify these tumors on the basis of immunohistochemical (IHC) staining of transcription factors, hormones, and other biomarkers.¹ Pituitary adenomas differentiate from pluripotent stem cells along one of three lineage pathways, depending on the following active transcription factors (TFs): pituitary transcription factor 1 (PIT-1), T-box transcription factor (TPIT), or steroidogenic factor-1 (SF-1). Rarely, two or more discrete pituitary adenomas from different lineages are identified in patients; however, the etiology remains unclear.² The incidence of multiple pituitary adenomas has been reported to be 1%–2% of all resected pituitary adenomas but is likely underestimated based on data from large autopsy series.^1–4 Pluri-hormonal adenomas are also rare entities in which a single tumor contains multiple TF lineages with one or more hormonal excesses.^1–3 Preoperative recognition of multiple or pluri-hormonal pituitary adenomas is rare, and most tumors are discovered incidentally upon autopsy, intraoperatively, or on histological analysis.^2,3,5

In cases of multiple synchronous pituitary adenomas, only one hormone excess syndrome is most frequently evident on clinical presentation and endocrine workup. Silent pituitary tumors positive for prolactin on immunohistochemistry are the most prevalent additional, incidentally found tumor in cases of multiple pituitary adenomas.⁵ This is particularly true in Cushing disease.^6,7 It is important to recognize the presence of multiple pituitary adenomas especially in the setting of hormonally active pituitary adenomas to provide optimal management for this subset of patients. Complete resection is curative for Cushing disease with the standard of care achieved through a transsphenoidal approach. Localization of the tumor presents a challenge because of suboptimal sensitivity of magnetic resonance imaging (MRI) in demonstrating microadenomas, the inconsistency of lateralization with inferior petrosal sinus sampling (IPSS), and delays in pathological analysis.^1,8,9 Additionally, the presence of an additional pituitary adenoma can obscure the microtumor through its large size and mass effect and can act as a “decoy lesion” during MRI, IPSS, and resection.⁶

Consideration of multiple pituitary tumors is necessary for successful resection. In a patient with a biochemical picture of Cushing disease, the demonstration of an adenoma with negative adrenocorticotrophic hormone (ACTH) immunostaining and the absence of postoperative hypoadrenalism may indicate the existence of a double adenoma. Few cases have described a lack of remission of an endocrinopathy after transsphenoidal resection due to the presence of an additional adenoma,^2,6,10 and even less so in the instance of the persistence of Cushing disease.⁶ We present a rare case of double pituitary adenomas in a patient presenting with Cushing disease who underwent two endoscopic endonasal transsphenoidal resections and immunostaining for prolactin and ACTH, respectively, with long-term normalization of her hypothalamic-pituitary-adrenal (HPA) axis.

Illustrative Case

History and Presentation

A 32-year-old female, gravida 0 para 0, with a history of a pituitary lesion and hyperprolactinemia presented to our institution for the evaluation for Cushing disease. Ten years earlier, the patient had presented to a gynecologist with hirsutism, galactorrhea, and oligomenorrhea. Her endocrine workup was remarkable for an elevated prolactin at 33.8 ng/mL (2.3–23.3 ng/mL), while follicle-stimulating hormone (FSH), luteinizing hormone (LH), and thyroid-stimulating hormone (TSH) levels were normal. No ACTH or cortisol levels were available. MRI demonstrated a 5 × 6 × 5–mm T1-weighted isointense pituitary lesion protruding into the suprasellar cistern due to a small sella size. She was treated with bromocriptine 2.5 mg daily for 5 years, with normalization of her prolactin level. Subsequent MRI demonstrated a stable lesion size and T1 and T2 hyperintensity in the region of the known pituitary lesion, considered to be posttreatment cystic change with proteinaceous contents and blood. After the normalization of her prolactin levels, she continued to have oligomenorrhea and abnormal hair growth. Polycystic ovaries were not visualized on ultrasound. She was started on oral contraceptives and then switched to the etonorgestrel implant.

A decade after initial presentation, she presented to endocrinology at our institution with 3 years of weight gain, hirsutism, and potential oligomenorrhea. Vital signs were stable (blood pressure: 122/86; heart rate: 72 beats/min), and facial fullness and striae on her bilateral breasts were appreciated on physical examination. She was taking isoniazid and pyridoxine for a recent diagnosis of latent tuberculosis and had discontinued bromocriptine 5 years earlier. Her weight was 66.3 kg and body mass index (BMI) was 23.9 kg/m². She reported that her maternal uncle had a pituitary tumor. Laboratory analysis was positive for elevated urinary free cortisol (UFC) of 109 µg per 24 hours (2.5–45 µg/24 h; Table 1) and nighttime salivary cortisol of 142 ng/mL (<100 ng/dL) with high-normal prolactin of 22.8 ng/mL (2.3–23.3 ng/dL) and normal FSH, LH, TSH, and thyroxine (T4). Dehydroepiandrosterone sulfate (DHEA-S) was 128 µg/dL (98.8–340.0 µg/dL). Imaging demonstrated a 4 × 4 × 4–mm pituitary lesion with decreased T1-weighted and increased central T2-weighted signal intensity in the left lateral pituitary (Fig. 1A–C). Desmopressin (Ferring Pharmaceuticals DDAVP) stimulation increased a basal ACTH of 49.9 pg/mL to ACTH of 91.2 pg/mL, and cortisol increased from 13.7 µg/dL to 21.2 µg/dL, consistent with neoplastic hypercortisolism. IPSS was performed, which showed a right-sided, central-to-peripheral ACTH gradient (Table 2). The patient elected to undergo endoscopic endonasal resection with the initial target as the left-lateral pituitary mass to achieve a cure for Cushing disease.

TABLE 1Urinary free cortisol at baseline and 3, 5, and 7 months after the primary resection

Variable	Baseline	3 Mos	5 Mos	7 Mos on Osilodrostat
Urinary free cortisol (4–50 µg/24 hrs)	109	134.2	125.4	40.3
Urinary creatinine (0.5–2.5 g/24 hrs)	0.995	1.17	1.42	1.11
Urinary vol (mL)	1950	2300	2100	2125

TABLE 2Preoperative inferior petrosal sinus sampling with corticorelin ovine triflutate 68 µg

Time (mins)	ACTH (pg/mL)					Prolactin (ng/mL)
	Peripheral	Petrosal Sinus		ACTH Ratio		Peripheral	Petrosal Sinus		Prolactin Ratio
	Peripheral	Rt	Lt	Rt	Lt	Peripheral	Rt	Lt	Rt	Lt
−5	50.6	225	1586	4.45	31.34	21	124	295	5.90	14.05
0	48.8	389	1376	7.97	28.20	22.2	185	198	8.33	8.92
3	69.8	4680	1333	67.05	19.1	22.1	396	32.5	17.92	1.47
5	80.9	4590	1623	56.74	20.06	22.1	436	32.2	19.73	1.46
10	112	4160	1660	37.14	14.82	20.2	367	42	17.90	2.05

ACTH or prolactin ratio = inferior petrosal sinus ACTH or prolactin/peripheral blood ACTH or prolactin.

Primary Resection and Outcomes

During the primary resection, abnormal tissue was immediately visible after a linear incision along the bottom of the dura, with an excellent plane of dissection. The inferomedial adenoma was distinct from the known left lateral lesion, and the resection was considered complete by the primary neurosurgeon. Subsequently, the left-sided adenoma was not pursued because of the historical prolactinoma diagnosis and an assumption that the newly discovered adenoma was the cause of ACTH hypersecretion. However, pathology of the inferomedial tumor was strongly and diffusely positive for prolactin (Fig. 2B), synaptophysin, and cytokeratin, with an Mindbomb Homolog-1 (MIB-1) proliferative index of 2.4%. ACTH, growth hormone (GH), FSH, LH, and TSH immunostaining were negative. TF immunohistochemistry was not available. On postoperative day (POD) 1, pituitary MRI was performed and demonstrated the unchanged 4-mm³ T1-weighted hypointense lesion with small central T2-weighted hyperintensity in the left lateral gland (Fig. 1D–F). Cortisol levels ranged from 9.7 to 76.2 µg/dL (4.8–19.5 µg/dL), and ACTH was 19.5 pg/mL (7.2–63.3 pg/mL) on POD 1.

Early reoperation was discussed with the patient based on the pathology and persistent hypercortisolism; however, she elected to pursue conservative management with close follow-up. Postoperative cortisol nadir was 4.8 µg/dL (4.8–19.5 µg/dL) on POD 2 during her 4-day hospital stay. DHEA-S was significantly decreased from baseline at 22.3 µg/dL (98.8–340.0 µg/dL) and a prolactin level of 3.4 ng/mL (2.3–23.3 ng/dL) was low-normal. No glucocorticoids were administered during her hospital course. There was no clinical evidence of vasopressin deficiency while she was an inpatient.

Three months postoperatively, the patient reported insomnia, poor hair quality, fatigue, nocturnal sweating, and continued increasing weight gain with fat accumulation in the supraclavicular and dorsal cervical area. She had one spontaneous menstrual period despite the use of etonogestrel implant. UFC was increased at 134.2 µg/24 hours (4–50 µg/24 h; Table 1). The 8:00 am serum cortisol was 10.2 µg/dL (5.0–25.0 µg/dL). She was started on osilodrostat 2 mg twice daily for her persistent hypercortisolism, and she reported some clinical improvement; however, she had continued elevation in her late-night salivary cortisol levels up to 7.0 nmol/L. Other endocrine lab work was normal, with a prolactin of 13.5 ng/mL (2.8–23.3 ng/mL) and TSH of 3.67 µIU/mL (0.4–4.0 µIU/mL). Her weight had increased by 4.9 kg to 71.2 kg with a BMI of 25.3 kg/m². Approximately 6 months postoperatively, she was amenable to a secondary resection targeting the remaining left lateral pituitary adenoma.

Secondary Resection and Outcomes

After obtaining adequate exposure for the secondary resection, the lesion in the left lateral aspect of the pituitary was targeted. The tumor was clearly identified and completely resected without intraoperative complication. IHC staining was diffusely positive for ACTH (Fig. 2E), synaptophysin, and cytokeratin with decreased reticulin and an MIB-1 index of 3.3%. Prolactin, GH, TSH, LH, and FSH immunostaining were negative. Postoperative cortisol monitoring demonstrated decreased levels, with a nadir of 2.0 µg/dL on POD 0. Levels of ACTH and DHEA-S were decreased at 4.4 pg/mL (7.2–63.3 pg/mL) and 13.3 µg/dL (98.8–340 µg/dL), respectively, on POD 1. Prolactin remained within the normal range at 8.2 ng/mL (2.8–23.3 ng/mL). The patient was started on intravenous hydrocortisone 50 mg every 8 hours for adrenal insufficiency. Postoperative symptoms of nausea, headache, and muscle weakness resolved with hydrocortisone administration. She was discharged on hydrocortisone 60 mg daily in divided doses for adrenal insufficiency and had no signs of vasopressin deficiency during her 2-day hospital course.

By 3 months, the patient reported decreased fatigue, myalgia, and insomnia and improved overall well-being and physical appearance. She was weaned down to a total daily dose of 20 mg of hydrocortisone and had lost 5.2 kg. Her menstruation returned while having an etonogestrel implant. Rapid ACTH stimulation was abnormal, with decreased cortisol at 30 minutes of 4.1 µg/dL (7.2–63.3 pg/mL) demonstrating continued adrenal insufficiency. Follow-up MRI demonstrated miniscule remaining left pituitary adenoma (Fig. 3). Seven months after her second surgery, she was started on 50 µg levothyroxine for primary hypothyroidism in the setting of slightly elevated TSH of 4.1 µIU/mL (0.4–4.0 µIU/mL) and a low-normal T4 of 0.8 ng/dL (0.7–1.5 ng/dL).

Two years after the second resection, the patient lost 10.1 kg (weight, 61.1 kg; BMI, 21.76 kg/m²). Her ACTH stimulation test became normal, and hydrocortisone therapy was discontinued. At the 2-year time point, the patient and her husband successfully conceived a child.

Patient Informed Consent

The necessary patient informed consent was obtained in this study.

Discussion

Double or multiple pituitary adenomas are discovered in 0.37%–2.6% of resected pituitary lesions.^3,4,6,11,12 A majority of multiple pituitary adenomas are not suspected before surgery with an inconclusive clinical presentation or endocrine laboratory workup.⁶ The presentation of multiple synchronous neoplasms is thought to be more common than having a single neoplasm with multiple lineages.¹ Studies have shown that additional pituitary adenomas are seen at a rate of 1.6%–3.3% in Cushing disease in studies including both contiguous and noncontiguous double pituitary adenomas.⁶ Additional pituitary adenomas that are hormonally active make up 40% of resected double pituitary adenomas, with most staining for gonadotroph adenoma.¹³ Overall, the most common incidental pituitary adenoma is prolactinoma,⁶ which occurs most frequently with GH or ACTH adenomas.⁵ In very rare instances, Cushing cases can present with hyperprolactinemia and Cushing synchronously.⁶ Hormonal secretion and clinical presentation are variable, with the pathology most often attributed to only one component of double pituitary adenoma.^3,14 The multiple-hit theory is the most common hypothesis for double pituitary adenoma etiology with coincidental monoclonal expansion of two or more lineages, which present with separate pseudo-capsules for each lesion.¹⁵

Observations

On presenting with Cushing disease, the differential diagnosis before the initial operation considered that the known left lateral pituitary adenoma could be a mixed tumor with both prolactin and ACTH lineages. Therefore, it was the initial target of the resection until discovering the second adenoma intraoperatively. With two distinct adenomas, the inferomedial adenoma was presumed to be the source of the ACTH hypersecretion and was subsequently resected. The left lesion was thought to be a prolactinoma and hormonally inactive after historical dopaminergic therapy and thus was not pursued during the initial surgery. However, pathology confirmed that the opposite was true. Few cases have also involved incidental pituitary tumors that look like the hormonally active adenoma and encourage resection of it, leaving the primary pituitary adenoma behind.^6,7 It has been reported that these “decoy lesions” can cause surgical failure and require secondary operations.^6,7,10,16 Intraoperative localization and confirmation of the adenoma classification may have also been helpful during the case, including tissue-based ACTH antibody assay,⁹ plasma ACTH measurements with a immunochemiluminometric method,¹⁷ or intraoperative ultrasound.^5,6

The inferomedial second tumor was not appreciated or reported throughout her serial MRI studies from 2010 to 2020. Interestingly, imaging did demonstrate the left pituitary adenoma that was medically treated as a prolactinoma, although it was later diagnosed as an ACTH-secreting lesion on IHC staining. Preoperative visualization of a pituitary adenoma in Cushing disease is reported to be limited, with a reported 50% incidence with negative MRI with standard 1.5 T.^1,18,19 MRI technical refinements in magnet strength, slice thickness, or enhanced spin sequences have increased sensitivity, but one-third of patients with Cushing disease still have negative scans.²⁰ Small prolactinomas, especially those near the cavernous sinus, are also notoriously difficult to visualize on MRI, although recent advances using co-registration of ¹¹C-methionine positron emission tomography–computed tomography with MRI (Met-PET/MRI^CR) may prove useful.²¹ Difficulty with preoperative visualization complicates a diagnosis of multiple adenomas, with or without multiple endocrinopathies, and negatively affects surgical planning. In a single-institution retrospective review of MRI in all cases of double pituitary tumors, only one of eight patients (12.5%) over 16 years of age had a positive MRI for double pituitary tumors and was diagnosed preoperatively.²

The patient’s preoperative IPSS demonstrated a right central-to-peripheral gradient. This was incongruent with the MRI demonstrating the single left-sided tumor. While IPSS is useful in confirming Cushing disease, its sensitivity for lateralization has been reported at only 59%–71%.⁹ With this in mind and a known left-sided adenoma on MRI, exploration of the right side of the pituitary was not originally planned. Ultimately, the left-sided adenoma was the source of ACTH hypersecretion, which remains incongruent with preoperative IPSS. It has been suggested that multiple pituitary adenomas in Cushing disease could further decrease its accuracy.^1,6

The patient’s initial historical prolactin levels (33.8 ng/dL) were lower than reported levels of 100–250 ng/dL for microadenoma and >250 ng/dL in cases of macroadenoma. Normally, in active single prolactinoma, prolactin secretion is correlated to size. We do not suspect that the presence of more than one pituitary adenoma would affect the level of prolactin hypersecretion.⁶ Slight elevations in prolactin can be attributed to causes such as pituitary stalk effect, medications, and physiological stimulation. During the 5 years of bromocriptine therapy, the effect on the inferomedial prolactinoma was unknown, as it was not appreciated on MRI. There are reports of prolactinomas being less responsive to dopaminergic agonist therapy in cases of double adenomas.^14,22 Upon resection of the inferomedial prolactinoma during the initial operation, there was no further change in the patient’s prolactin levels, which could most likely be attributed to prior dopaminergic therapy. Unfortunately, the initial endocrine laboratory workup did not include levels of ACTH or cortisol. In addition to hyperprolactinemia, Cushing disease can also present with changes in menstruation. After the secondary resection and removal of the ACTH-secreting pituitary adenoma, the patient’s oligomenorrhea resolved and she achieved pregnancy. Retrospectively, it remains unclear if the prolactinoma was once truly active hormonally.

Lessons

The rare presence of two pituitary adenomas can complicate the diagnosis, medical and surgical management, and long-term outcomes for patients. A complete endocrine workup is essential when a pituitary adenoma is suspected and can help screen for pluri-hormonal and multiple pituitary adenomas. In our patient, it is unknown when the onset of hypercortisolism was with the limited initial hormonal workup.

Currently, localizing and resecting the hormonally active adenoma in double or multiple pituitary adenomas remain a challenge, with limitations in preoperative imaging and intraoperative measures. After encountering the additional inferomedial lesion during surgery, resection of both adenomas during the initial surgery may have been prudent to ensure the resolution of Cushing disease. Although exploration for additional pituitary adenomas is not usually recommended, it could be considered in cases of multiple pituitary adenomas and uncertainty of the culprit of Cushing disease.

The current characterization of pituitary tumors by the World Health Organization includes immunohistochemistry for both transcription factors and pituitary hormones, with clinical usefulness to be determined by future studies. Multiple lineages can occur mixed in a single pituitary adenoma or across different noncontiguous adenomas and can only be determined by TF immunostaining. The left ACTH-staining lesion in our patient had some shrinkage and MRI changes, which may have been a response to dopaminergic therapy. Full characterization of the tumor cell lineages in this case remains undetermined without staining for TFs.

In conclusion, we report a rare case of Cushing disease concurrent with a prolactinoma leading to the need for repeat resection. This is one of the few reported cases of a double pituitary adenoma leading to a lack of biochemical remission of hypercortisolism after the initial surgery. Strategies for localization of the active tumor in double pituitary adenomas are essential for primary surgical success and the resolution of endocrinopathies.

Author Contributions

Conception and design: Zwagerman, Tavakoli, Shah, Findling. Acquisition of data: Zwagerman, Armstrong, Tavakoli, Shah, Ioachimescu, Findling. Analysis and interpretation of data: Zwagerman, Armstrong, Tavakoli, Shah, Coss, Ioachimescu, Findling. Drafting of the article: Zwagerman, Armstrong, Shah. Critically revising the article: Zwagerman, Armstrong, Tavakoli, Shah, Ioachimescu, Findling. Reviewed submitted version of the manuscript: Zwagerman, Armstrong, Tavakoli, Shah, Laing, Ioachimescu, Findling. Approved the final version of the manuscript on behalf of all authors: Zwagerman. Statistical analysis: Armstrong, Shah. Administrative/technical/material support: Zwagerman, Armstrong, Shah. Study supervision: Zwagerman, Tavakoli, Shah, Laing.

References

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2↑Roberts S, Borges MT, Lillehei KO, Kleinschmidt-DeMasters BK. Double separate versus contiguous pituitary adenomas: MRI features and endocrinological follow up. Pituitary. 2016;19(5):472–481.
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From https://thejns.org/caselessons/view/journals/j-neurosurg-case-lessons/6/22/article-CASE23485.xml

Filed under: Cushing's, pituitary, Rare Diseases, symptoms, Treatments | Tagged: Cushing's Disease, endoscopic, hirsuitism, Inferior petrosal sinus sampling, IPSS, Pituitary adenoma, prolactin, weight | Leave a comment »

Ultrasound-Guided Jugular Vein Access for Inferior Petrosal Sinus Sampling: A Safe and Feasible Technique

Posted on December 11, 2025 by MaryO

Abstract

Pituitary Cushing’s disease (CD) results from excessive adrenocorticotropic hormone (ACTH) secretion, usually due to a pituitary adenoma. This report describes the diagnostic approach and management of a complex case of CD in a patient with multiple comorbidities, highlighting a hybrid technique for inferior petrosal sinus sampling (IPSS) when standard access fails.

A woman with poorly controlled diabetes, obesity, chronic kidney disease (CKD), and hypertension presented with suspected Cushing’s syndrome. Despite normal urinary free cortisol (UFC) levels (likely influenced by renal dysfunction), clinical suspicion prompted further testing, which revealed an inverted cortisol rhythm and lack of suppression on low-dose dexamethasone. High-dose suppression indicated a pituitary source. MRI findings were inconclusive. To confirm the diagnosis, bilateral IPSS was attempted. Right petrosal sinus catheterization via femoral access was successful; however, left-sided access failed. An alternative, ultrasound-guided direct left internal jugular puncture was performed, allowing complete sampling. A central-to-peripheral ACTH gradient >2 at baseline and >3 after desmopressin confirmed a pituitary source. The patient subsequently underwent successful transsphenoidal resection, achieving postoperative biochemical remission.

IPSS remains the gold standard for distinguishing central from ectopic ACTH production. While bilateral femoral access is standard, anatomical variants may necessitate alternative routes. This case demonstrates the feasibility and safety of combining femoral and direct jugular access to complete IPSS when conventional approaches are limited.

This is the first reported case of IPSS performed using a hybrid right femoral and left ultrasound-guided jugular approach, offering a practical alternative when femoral access is not feasible and reinforcing the diagnostic value of IPSS in challenging cases.

Introduction

Pituitary Cushing’s disease (CD) is caused by excessive secretion of adrenocorticotropic hormone (ACTH), typically due to a pituitary adenoma. It represents the most common cause of endogenous Cushing’s syndrome, accounting for approximately 70% of ACTH-dependent cases [1,2]. The diagnostic approach often requires dynamic hormonal testing and neuroimaging; however, distinguishing pituitary from ectopic ACTH secretion remains a clinical challenge [3].

Inferior petrosal sinus sampling (IPSS), first described by Oldfield EH and Doppman JL in 1977, is considered the gold standard for confirming a pituitary origin when biochemical and imaging findings are inconclusive [4-6]. Bilateral catheterization via femoral venous access is the usual approach, guided by digital subtraction angiography (DSA) [4,5]. However, anatomical variants, thrombosis, and technical difficulties can impede standard catheterization, necessitating alternative strategies such as direct ultrasound-guided internal jugular puncture [7].

This report presents a patient with multiple comorbidities and suspected CD in whom a hybrid IPSS approach was successfully performed after failed standard access.

Case Presentation

A female patient with a history of poorly controlled diabetes, obesity, chronic kidney disease (CKD), and hypertension was admitted with suspected Cushing’s syndrome. Initial evaluation revealed normal urinary free cortisol (UFC), likely underestimated due to renal dysfunction. Because of high clinical suspicion, circadian cortisol rhythm was assessed, showing inversion with higher evening than morning levels, supporting hypercortisolism.

A low-dose dexamethasone suppression test (LDDST; 1 mg) failed to suppress cortisol, confirming endogenous hypercortisolism. A high-dose dexamethasone suppression test (HDDST; 8 mg) demonstrated 80% cortisol suppression, suggesting a pituitary source of ACTH overproduction.

Pituitary MRI revealed a poorly defined hypointense nodular area, inconclusive for microadenoma (Figure 1A). To confirm the central origin, bilateral inferior petrosal sinus sampling (IPSS) was performed (Figures 1B–1E).

(A)-Contrast-enhanced-pituitary-MRI-showing-a-hypointense-nodule-in-the-left-half-of-the-gland,-which-was-inconclusive;-(B)-right-internal-jugular-vein-access-achieved,-while-left-jugular-access-was-not-possible-via-this-route;-(C-and-D)-dual-inferior-petrosal-sinus-catheterization-with-right-sided-access-via-the-femoral-vein-and-left-sided-access-via-direct-jugular-puncture;-(E)-ultrasound-guided-placement-of-the-venous-sheath.

Figure 1: (A) Contrast-enhanced pituitary MRI showing a hypointense nodule in the left half of the gland, which was inconclusive; (B) right internal jugular vein access achieved, while left jugular access was not possible via this route; (C and D) dual inferior petrosal sinus catheterization with right-sided access via the femoral vein and left-sided access via direct jugular puncture; (E) ultrasound-guided placement of the venous sheath.

Initial access was established via the bilateral femoral veins with placement of 5 Fr introducer sheaths in both. Due to anatomical complexity and inability to access the left internal jugular vein via the femoral route, a direct ultrasound-guided left jugular puncture was performed. A separate 5 Fr introducer sheath was placed directly into the left internal jugular vein under ultrasound guidance (US guidance). Catheterization was performed using 5 Fr vertebral diagnostic catheters, facilitated by a micro-guidewire.

Correct positioning within the petrosal sinuses was subsequently confirmed by contrast injection. The results demonstrated accurate catheter placement in the inferior petrosal sinuses (adequate prolactin levels), with an ACTH central-to-peripheral gradient greater than 2 at baseline and greater than 3 after desmopressin, thus confirming a pituitary source for the pathology (Tables 1–2).

Peripheral	Right IPS	Left IPS
16.5 ng/mL	41.2 ng/mL	63.7 ng/mL

Table 1: Prolactin concentrations obtained via inferior petrosal sinus sampling at baseline.

IPS: Inferior Petrosal Sinus.

Time Point	Peripheral	Right IPS	Left IPS
Basal	27.5 pg/mL	77.1 pg/mL	106 pg/mL
Desmopressin 5 min	28.3 pg/mL	168 pg/mL	221 pg/mL
Desmopressin 10 min	27.9 pg/mL	32 pg/mL	80 pg/mL

Table 2: ACTH concentrations obtained via inferior petrosal sinus sampling at baseline and at 5 and 10 minutes after desmopressin stimulation.

IPS: Inferior Petrosal Sinus; ACTH: Adrenocorticotropic hormone.

The patient underwent endonasal transsphenoidal resection of an ACTH-secreting pituitary microadenoma. Postoperatively, serum cortisol fell to <5 µg/dL, indicating secondary adrenal insufficiency, and physiologic glucocorticoid replacement was initiated. Urine output remained normal (no evidence of vasopressin deficiency), and steroid replacement was titrated without adrenal crisis.

Discussion

Diagnostic considerations

CKD can lead to falsely normal UFC values due to impaired renal clearance of cortisol metabolites [8]. Therefore, alternative biochemical tests such as late-night serum cortisol or dexamethasone suppression are recommended in these patients [1,3]. The high-dose dexamethasone suppression observed here supported a pituitary origin, but confirmation by IPSS was critical given the inconclusive MRI findings.

Inferior petrosal sinus sampling

Since its introduction, IPSS has become the reference standard for distinguishing pituitary from ectopic ACTH production, with reported sensitivity and specificity of approximately 96% and 100%, respectively [4-6,9]. The test involves measuring ACTH gradients between central (petrosal) and peripheral samples, values ≥2 at baseline or ≥3 after corticotropin-releasing hormone (CRH) or desmopressin stimulation indicate a central source [5,9].

Desmopressin stimulation

Although CRH has traditionally been used, desmopressin is an effective and safe alternative that achieves comparable diagnostic accuracy [10]. In our case, desmopressin successfully elicited a diagnostic gradient, confirming the pituitary source.

Technical challenges and hybrid approach

Although the conventional IPSS technique uses bilateral femoral access, the procedure was originally performed via direct jugular puncture [2]. Variations in venous anatomy, hypoplasia, or catheterization failure may necessitate alternative routes. Direct ultrasound-guided jugular puncture offers an effective solution, minimizing procedural time and radiation exposure, and reducing the risk of complications such as cervical hematoma. Our case illustrates that combining femoral and direct jugular access allows complete bilateral sampling without compromising safety.