The Challenge of Obesity in Diagnosing Cushing’s Syndrome and Strategies to Improve Methods

The effects of obesity on the diagnosis of Cushing’s syndrome and strategies to alter the traditional approaches have been addressed in a new review study.

The study, “Diagnosis and Differential Diagnosis of Cushing’s Syndrome,” appeared in The New England Journal of Medicine. The author was Dr. Lynn D. Loriaux, MD and PhD, and a professor of medicine at the Division of Endocrinology, Diabetes and Clinical Nutrition at the School of Medicine, Oregon Health & Science University (OHSU), in Portland, Oregon.

Traditionally, exams of patients with glucocorticoid excess focused on the presence of changes in anabolism (the chemical synthesis of molecules). Given the increase in obesity in the general population, changes in anabolism can no longer distinguish Cushing’s syndrome from metabolic syndrome.

However, analyses of anti-anabolic changes of cortisol – including osteopenia (lower bone density), thin skin, and ecchymoses (injury that causes subcutaneous bleeding) – are an effective way to make this distinction.

The worldwide prevalence of metabolic syndrome in obese people is estimated at about 10%. Conversely, the incidence of undiagnosed Cushing’s syndrome is about 75 cases per 1 million people.

Cushing’s and metabolic syndrome share significant clinical similarities, including obesity, hypertension, and type 2 diabetes. Therefore, “making the diagnosis is the least certain aspect in the care of patients with [Cushing’s],” Loriaux wrote.

Regarding a physical examination, patients with osteoporosis, reduced skin thickness in the middle finger, and three or more ecchymoses larger than 1 cm in diameter and not associated with trauma are more likely to have Cushing’s. Researchers estimate the probability of people with all three of these symptoms having Cushing’s syndrome is 95%.

Measuring 24-hour urinary-free cortisol levels allows the assessment of excess glucocorticoid effects, typical of Cushing’s syndrome. The test, which should be done with the most stringent techniques available, averages the augmented secretion of cortisol in the morning and the diminished secretion in the afternoon and at night.

Dexamethasone suppression is one of the currently used screening tests for Cushing’s syndrome. Patients with obesity and depression should not show decreased plasma cortisol levels when dexamethasone is suppressed. However, given its low estimated predictive value (the proportion of positive results that are “true positives”), “this test should not influence what the physician does next and should no longer be used” to screen for Cushing’s, the author wrote.

Some patients may show evidence of Cushing’s syndrome at a physical examination, but low urinary free cortisol excretion. This may be due to glucocorticoids being administered to the patient. In this case, the glucocorticoid must be identified and discontinued. Periodic Cushing’s assessments that measure urinary free cortisol should be performed.

The opposite can also occur: no clinical symptoms of Cushing’s, but elevated urinary free cortisol excretion and detectable plasma levels of the hormone corticotropin. In these patients, the source of corticotropin secretion, which can be a tumor or the syndrome of generalized glucocorticoid resistance, must be determined.

The disease process can be corticotropin-dependent or independent, depending on whether the hormone is detectable. Corticotropin in Cushing’s syndrome can come from the pituitary gland (eutopic) or elsewhere in the body (ectopic).

Loriaux recommends that the source of corticotropin secretion be determined before considering surgery. Up to 40% of patients with pituitary adenomas have nonfunctioning tumors (the tumor does not produce any hormones) and the corticotropin source is elsewhere. If misdiagnosed, patients will likely undergo an unnecessary surgery, with a mortality rate of 1%.

Patients with an ectopic source of corticotropin should undergo imaging studies in the chest, followed by abdominal and pelvic organs. If these tests fail to detect the source, patients should undergo either the blockade of cortisol synthesis or an adrenalectomy (removal of adrenal glands).

However, corticotropin-independent Cushing’s is usually caused by a benign adrenal tumor that uniquely secretes cortisol.

“Such tumors can be treated successfully with laparoscopic adrenalectomy,” Loriaux wrote. If the tumor secretes more than one hormone, it is likely malignant. Surgical to remove the tumor and any detectable metastases should be conducted.

Overall, “the treatment for all causes of [Cushing’s syndrome], other than exogenous glucocorticoids, is surgical, and neurosurgeons, endocrine surgeons, and cancer surgeons are needed,” Loriaux wrote in the study.

“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.”

From https://cushingsdiseasenews.com/2017/10/24/diagnosing-cushings-syndrome-amid-challenge-of-obesity-and-strategies-to-improve-methods/

Long-acting pasireotide safe, effective for recurrent Cushing’s disease

October 20, 2017

In patients with persistent or recurring Cushing’s disease after surgery, monthly pasireotide was safe and effective, leading to normal urinary free cortisol levels in about 40% of patients after 12 months, according to findings from a phase 3 clinical trial.

“Surgical resection of the causative pituitary adenoma is the first-line treatment of choice for most patients with Cushing’s disease, which leads to remission in greater than 75% of patients if done by an expert pituitary surgeon,” Andre Lacroix, MD, professor in the department of medicine at University of Montreal teaching hospital, and colleagues wrote in the study background. “However, surgery is not always successful, and disease recurrence can occur several years after initial remission, while some patients refuse or are not candidates for surgery. As a result, many patients require additional treatment options.”

Lacroix and colleagues analyzed data from 150 patients with a confirmed diagnosis of persistent, recurrent or new Cushing’s disease with mean urinary free cortisol level concentration 1.5 to five times the upper limit of normal, normal or greater than normal plasma and confirmed pituitary source of Cushing’s disease. Patients were recruited between December 2011 and December 2014; those who received mitotane therapy within 6 months, pituitary irradiation within 10 years or previous pasireotide treatment were excluded. Researchers randomly assigned patients to 10 mg (n = 74) or 30 mg (n = 76) monthly intramuscular pasireotide (Signifor LAR, Novartis) for 12 months, with investigators and patients masked to the group allocation and dose. Pasireotide was up-titrated from 10 mg to 30 mg or from 30 mg to 40 mg at month 4, or at month 7, 9 or 12 if urinary free cortisol concentrations remained greater than 1.5 times the upper limit of normal. At month 12, patients considered to be receiving clinical benefit from the therapy (mean urinary free cortisol concentration at or less than the upper limit of normal) could continue to receive it during an open-ended extension phase. The primary outcome was to assess the proportion of patients achieving mean urinary free cortisol concentration less than or equal to the upper limit of normal by month 7, regardless of dose.

Within the cohort, 41.9% of patients in the 10-mg group and 40.8% of patients in the 40-mg group met the primary endpoint at month 7, whereas 5% of patients in the 10-mg group and 13% of patients in the 40-mg group achieved partial control. Researchers did not observe between-sex differences or differences in response among those who did or did not undergo previous surgery.

The number of patients who achieved the primary endpoint at month 7 without an up-titration in dose was smaller, but not significantly different between the 10-mg and 40-mg dose groups (28.4% and 31.6%, respectively), according to researchers. Among those who received an up-titration in dose in the 10-mg and 40-mg groups (42% and 37%, respectively), 32% and 25%, respectively, were considered responders at month 7.

Researchers also observed improvements in several metabolic parameters during the 12-month course of treatment with both doses, including improvements in systolic and diastolic blood pressure; reductions in waist circumference, BMI and body weight; and improvement in scores for the Cushing’s Quality of Life questionnaire. The most common adverse events were hyperglycemia, diarrhea, cholelithiasis, diabetes and nausea.

The researchers noted that, in both dose groups, the reductions in mean urinary free cortisol concentration were observed within 1 month, with concentrations remaining below baseline levels for the 12-month study period.

“This large phase 3 trial showed that long-acting pasireotide administered for 12 months can reduce [median urinary free cortisol] concentrations, is associated with improvements in clinical signs and [health-related quality of life] and has a similar safety profile to that of twice-daily pasireotide,” the researchers wrote, adding that the long-acting formulation provides a convenient monthly administration schedule. – by Regina Schaffer

Disclosures: Novartis funded this study. Lacroix reports he has received grants and personal fees as a clinical investigator, study steering committee member and advisory board member for Novartis, Stonebridge and UpToDate. Please see the study for all other authors’ relevant financial disclosures.

From https://www.healio.com/endocrinology/adrenal/news/in-the-journals/%7B55988079-312b-478d-8788-036a465b1881%7D/long-acting-pasireotide-safe-effective-for-recurrent-cushings-disease

Cushing’s Testing at NIH

Rank Status Study
1 Recruiting Study to Evaluate CORT125134 in Patients With Cushing’s Syndrome

Condition: Cushing’s Syndrome
Intervention: Drug: CORT125134
2 Recruiting Cushing’s Disease Complications

Condition: Cushing’s Disease
Intervention: Other: Exams and questionnaires
3 Recruiting The Accuracy of Late Night Urinary Free Cortisol/Creatinine and Hair Cortisol in Cushing’s Syndrome Diagnosis

Condition: Cushing Syndrome
Intervention:
4 Recruiting Treatment for Endogenous Cushing’s Syndrome

Condition: Endogenous Cushing’s Syndrome
Intervention: Drug: COR-003
5 Recruiting Saliva Cortisol Measurement as a Screening Test for Suspicious Cushings Syndrome in Children.

Condition: Cushings Syndrome
Intervention: Other: Children refered to the obesity clinic
6 Recruiting Safety and Efficacy of LCI699 for the Treatment of Patients With Cushing’s Disease

Condition: Cushing’s Disease
Intervention: Drug: LCI699
7 Recruiting Treatment of Cushing’s Disease With R-roscovitine

Condition: Cushings Disease
Intervention: Drug: R-roscovitine
8 Recruiting A Study of ATR-101 for the Treatment of Endogenous Cushing’s Syndrome

Condition: Cushing Syndrome
Interventions: Drug: ATR-101;   Drug: Placebos
9 Recruiting Evaluation of 68Ga-DOTATATE PET/CT, Octreotide and F-DOPA PET Imaging in Patients With Ectopic Cushing Syndrome

Condition: Cushing Syndrome
Interventions: Drug: F-DOPA PET Scan;   Drug: Mifepristone;   Drug: Ga-DOTATATE;   Drug: Octreoscan;   Other: CT, MRI
10 Not yet recruiting Endocrine Cardiomyopathy in Cushing Syndrome: Response to Cyclic GMP PDE5 inhibitOrs

Condition: Cushing’s Syndrome Cardiomyopathy
Intervention: Drug: Tadalafil
11 Recruiting Long-term Beneficial Metabolic Effects of Adrenalectomy in Subclinical Cushing’s Syndrome of Adrenal Incidentaloma

Condition: Cushing Syndrome
Intervention: Procedure: surgery
12 Recruiting Long Term Safety and Efficacy of Pasireotide s.c. in Patients With Cushing’s Disease

Condition: Cushings Disease
Intervention: Drug: SOM230
13 Recruiting New Imaging Techniques in the Evaluation of Patients With Ectopic Cushing Syndrome

Condition: Cushing Syndrome
Interventions: Drug: Pentetreotide;   Drug: 18-F-fluorodeoxyglucose;   Drug: (18F)-L-3,4-dihydroxyophenylalanine (18F-DOPA)
14 Not yet recruiting Targeting Iatrogenic Cushing’s Syndrome With 11β-hydroxysteroid Dehydrogenase Type 1 Inhibition

Condition: Iatrogenic Cushing’s Disease
Interventions: Drug: AZD4017 and prednisolone;   Drug: Placebo Oral Tablet and prednisolone
15 Not yet recruiting Assessment of Persistent Cognitive Impairment After Cure of Cushing’s Disease

Condition: Cushing’s Disease
Intervention: Device: Virtual radial task in 3D
16 Recruiting Biomarker Expression in Patients With ACTH-Dependent Cushing’s Syndrome Before and After Surgery

Condition: Cushing’s Syndrome
Intervention:
17 Recruiting Efficacy and Safety Evaluation of Osilodrostat in Cushing’s Disease

Condition: Cushing’s Disease
Interventions: Drug: osilodrostat;   Drug: osilodrostat Placebo
18 Recruiting Effects of Metyrapone in Patients With Endogenous Cushing’s Syndrome

Condition: Cushing’s Syndrome
Intervention: Drug: metyrapone
19 Recruiting Adrenal Venous Sampling in Patients With Overt or Subclinical Cushings Syndrome, and Bilateral Adrenal Tumors

Condition: Cushing Syndrome
Intervention: Radiation: Adrenal venous sampling
20 Recruiting Glycemic Fluctuations in Newly Diagnosed Growth Hormone-Secreting Pituitary Adenoma and Cushing Syndrome Subjects

Condition: Pituitary Adenoma
Intervention: Device: continuous glucose monitoring
Rank Status Study
21 Recruiting Targeted Therapy With Gefitinib in Patients With USP8-mutated Cushing’s Disease

Conditions: Cushing’s Disease;   Corticotrophin Adenoma
Intervention: Drug: Gefitinib
22 Recruiting Cardiac Steatosis in Cushing’s Syndrome

Conditions: Endocrine System Disease;   Cardiovascular Imaging
Intervention: Other: 1H magnetic resonance spectroscopy and CMRI
23 Recruiting Study of Management of Pasireotide-induced Hyperglycemia in Adult Patients With Cushing’s Disease or Acromegaly

Conditions: Cushing’s Disease;   Acromegaly
Interventions: Drug: Pasireotide s.c.;   Drug: Sitagliptin;   Drug: Liraglutide;   Drug: Insulin;   Drug: Pasireotide LAR;   Drug: Metformin
24 Recruiting Study of Efficacy and Safety of Osilodrostat in Cushing’s Syndrome

Conditions: Cushing’s Syndrome;   Ectopic Corticotropin Syndrome;   Adrenal Adenoma;   Adrenal Carcinoma;   AIMAH;   PPNAD
Intervention: Drug: Osilodrostat
25 Recruiting Effects of Hormone Stimulation on Brain Scans for Cushing s Disease

Condition: Pituitary Neoplasm
Intervention: Drug: Acthrel
26 Recruiting Does Serum-DXM Increase Diagnostic Accuracy of the Overnight DXM Suppression Test in the Work-up of Cushing’s Syndrome?

Conditions: Cushing’s Syndrome;   Adrenal Incidentalomas;   Alcoholism;   Obesity
Intervention:
27 Recruiting Adrenalectomy Versus Follow-up in Patients With Subclinical Cushings Syndrome

Condition: Adrenal Tumour With Mild Hypercortisolism
Intervention: Procedure: Adrenalectomy
28 Recruiting Study of Adrenalectomy Versus Observation for Subclinical Hypercortisolism

Conditions: Hypercortisolism;   Cushing Syndrome
Interventions: Procedure: Adrenalectomy;   Other: Observation
29 Not yet recruiting Dynamic Hormone Diagnostics in Endocrine Disease

Conditions: Adrenal Insufficiency;   Congenital Adrenal Hyperplasia;   Cushing Syndrome;   Growth Hormone Deficiency;   Acromegaly;   Primary Hyperaldosteronism
Intervention: Other: 27 hour subcutaneous fluid sampling
30 Recruiting An Investigation of Pituitary Tumors and Related Hypothalmic Disorders

Conditions: Abnormalities;   Craniopharyngioma;   Cushing’s Syndrome;   Endocrine Disease;   Pituitary Neoplasm
Intervention:
31 Recruiting Ga-68-DOTATOC -PET in the Management of Pituitary Tumours

Condition: Pituitary Tumours
Intervention: Procedure: Gallium-68 DOTATOC PET
32 Recruiting Efficacy of Mifepristone in Males With Type 2 Diabetes Mellitus

Conditions: Type 2 Diabetes Mellitus;   Insulin Resistance
Interventions: Drug: Mifepristone 600 mg daily;   Drug: Placebo
33 Recruiting Targeted Therapy With Lapatinib in Patients With Recurrent Pituitary Tumors Resistant to Standard Therapy

Conditions: Pituitary Adenomas;   Prolactinomas
Intervention: Drug: Lapatinib
34 Recruiting Mutations of Glucocorticoid Receptor in Bilateral Adrenal Hyperplasia

Condition: General Glucocorticoid Resistance
Intervention: Genetic: blood collection for mutation characterization
35 Recruiting Defining the Genetic Basis for the Development of Primary Pigmented Nodular Adrenocortical Disease (PPNAD) and the Carney Complex

Conditions: Cushing’s Syndrome;   Hereditary Neoplastic Syndrome;   Lentigo;   Neoplasm;   Testicular Neoplasm
Intervention:
36 Not yet recruiting Reduction by Pasireotide of the Effluent Volume in High-output Enterostomy in Patients Refractory to Usual Medical Treatment

Condition: Enterostomy
Interventions: Drug: Pasireotide;   Drug: Placebo
37 Recruiting Mifepristone for Breast Cancer Patients With Higher Levels of Progesterone Receptor Isoform A Than Isoform B.

Condition: Breast Cancer
Intervention: Drug: Mifepristone
38 Recruiting SOM230 Ectopic ACTH-producing Tumors

Condition: Ectopic ACTH Syndrome
Intervention: Drug: Pasireotide
39 Recruiting Decreasing Rates of Intraurethral Catheterization Postoperatively in Spine Surgery

Condition: Post-operative Urinary Retention
Interventions: Drug: Tamsulosin;   Drug: Placebo
40 Recruiting Adrenal Tumors – Pathogenesis and Therapy

Conditions: Adrenal Tumors;   Adrenocortical Carcinoma;   Cushing Syndrome;   Conn Syndrome;   Pheochromocytoma
Intervention:

Diagnosis and Differential Diagnosis of Cushing’s Syndrome

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 .

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

Osilodrostat maintained cortisol control in Cushing’s syndrome

Osilodrostat, a drug that normalized cortisol in 89% of patients with Cushing’s syndrome who took it during a phase II study, continued to exert a sustained benefit during a 31-month extension phase.

In an intent-to-treat analysis, all of the 16 patients who entered the LINC-2 extension study responded well to the medication, with no lapse in cortisol control, Rosario Pivonello, MD, said at the annual meeting of the Endocrine Society.

“We also saw significant improvements in systolic and diastolic blood pressure and decreases in fasting plasma glucose,” said Dr. Pivonello of the University of Naples Federico II, Italy. “Surprisingly, after 31 months, we also observed declines in body mass index and weight.”

Osilodrostat, made by Novartis, is an oral inhibitor of 11 beta–hydroxylase. The enzyme catalyzes the last step of cortisol synthesis in the adrenal cortex. The drug was granted orphan status in 2014 by the European Medicines Agency.

In the LINC-2 study, 19 patients took osilodrostat at an initial dose of either 4 mg/day or 10 mg/day, if baseline urinary-free cortisol exceeded three times the upper normal limit. The dose was escalated every 2 weeks to up to 60 mg/day, until cortisol levels were at or below the upper limit of normal. In this study, the main efficacy endpoint was normalization of cortisol, or at least a 50% decrease from baseline at weeks 10 and 22.

Overall response was 89%. Osilodrostat treatment reduced urinary-free cortisol in all patients, and 79% had normal cortisol levels at week 22. The most common adverse events were asthenia, adrenal insufficiency, diarrhea, fatigue, headache, nausea, and acne. New or worsening hirsutism and/or acne were reported among four female patients, all of whom had increased testosterone levels.

The LINC-2 extension study enrolled 16 patients from the phase II cohort, all of whom had responded to the medication. They were allowed to continue on their existing effective dose through the 31-month period.

Dr. Pivonello presented response curves that tracked cortisol levels from treatment initiation in the LINC-2 study. The median baseline cortisol level was about 1,500 nmol per 24 hours. By the fourth week of treatment, this had normalized in all of the patients who entered the extension phase. The response curve showed continued, stable cortisol suppression throughout the entire 31-month period.

Four patients dropped out during the course of the study. Dr. Pivonello didn’t discuss the reasons for these dropouts. He did break down the results by response, imputing the missing data from these four patients. In this analysis, the majority (87.5%) were fully controlled, with urinary-free cortisol in the normal range. The remainder were partially controlled, experiencing at least a 50% decrease in cortisol from their baseline levels. These responses were stable, with no patient experiencing loss of control over the follow-up period.

The 12 remaining patients are still taking the medication, and they experienced other clinical improvements as well. Systolic blood pressure decreased by a mean of 2.2% (from 130 mm Hg to 127 mm Hg). Diastolic blood pressure also improved, by 6% (from 85 mm Hg to 80 mm Hg).

Fasting plasma glucose dropped from a mean of 89 mg/dL to 82 mg/dL. Weight decreased from a mean of 84 kg to 74 kg, with a corresponding decrease in body mass index, from 29.6 kg/m2 to 26.2 kg/m2.

Serum aldosterone decreased along with cortisol, dropping from a mean of 168 pmol/L to just 19 pmol/L. Adrenocorticotropic hormone increased, as did 11-deoxycortisol, 11-deoxycorticosterone, and testosterone.

Pituitary tumor size was measured in six patients. It increased in three and decreased in three. Dr. Pivonello didn’t discuss why this might have occurred.

The most common adverse events were asthenia, adrenal insufficiency, diarrhea, fatigue, headache, nausea, and acne. These moderated over time in both number and severity.

However, there were eight serious adverse events among three patients, including prolonged Q-T interval on electrocardiogram, food poisoning, gastroenteritis, headache, noncardiac chest pain, symptoms related to pituitary tumor (two patients), and uncontrolled Cushing’s syndrome.

Two patients experienced hypokalemia. Six experienced mild events related to hypocortisolism.

Novartis is pursuing the drug with two placebo-controlled phase III studies (LINC-3 and LINC-4), Dr. Pivonello said. An additional phase II study is being conducted in Japan.

Dr. Pivonello has received consulting fees and honoraria from Novartis, which sponsored the study.

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