Diagnosis guide for clinicians

Cushing disease and endogenous Cushing syndrome: when to suspect it and what to test

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Cushing disease, caused by an ACTH-secreting pituitary tumor, is the most common cause of endogenous Cushing syndrome, per the 2021 Pituitary Society consensus.Source Pituitary Society 2021 consensus

This guide covers testing for endogenous Cushing syndrome first, because guidelines look for the cause, including a pituitary tumor, only after hypercortisolism is confirmed.

Source Endocrine Society guideline

The Endocrine Society warns that if Cushing syndrome is not considered, the diagnosis is all too often delayed, since its features overlap with common conditions.

Source Endocrine Society guideline

2 to 3 per millionYearly incidence of endogenous Cushing syndrome in European population studies cited by the Endocrine SocietyEndocrine Society guideline

66%Share of 481 European registry patients whose Cushing syndrome was pituitary-dependent, which is Cushing diseaseEuropean Registry on Cushing's syndrome

38 monthsMean time from first symptoms to diagnosis of pituitary Cushing syndrome, in a meta-analysis of 5367 patientsTime to diagnosis meta-analysis

E24.0ICD-10-CM code, pituitary-dependent Cushing's diseaseNLM ICD-10-CM lookup

Orphanet recordORPHA:96253 ↗

Inheritance

Not applicable

Age of onset

Adult

Prevalence

1 to 9 per 100,000 point prevalence, Europe

Also called

Corticotroph pituitary adenoma, Pituitary corticotroph micro-adenoma, Pituitary-dependent Cushing syndrome

Live from Orphanet (INSERM) via Orphadata, licensed CC BY 4.0, data version 2026-06-23.

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Patterns to test Red flags Often mistaken for What to test Family screening ICD-10 codes Once confirmed For the patient

Patterns that should prompt a test for Cushing disease

Each sign below is common on its own, which is why Cushing disease is missed. Published studies describe these combinations as the picture to act on. Rows are ordered from the highest published figure to the lowest, within each kind of measure.

Where testing finds it

Share of each screened or biopsied group found to have Cushing disease, from the cited studies. A bar spans the lowest to the highest published figure.

1
Resistant hypertension
Patients with resistant hypertension in Brazil, 423 in all, screened for subclinical hypercortisolism; none had overt Cushing syndrome
Hypercortisolism was confirmed in 8.0% after an abnormal DST and 2 raised late-night salivary cortisols, with no overt Cushing syndrome (Martins 2012).Martins 2012 resistant hypertension study
8%
2
Osteoporosis with a T-score of -2.5 or lower+Vertebral fractures+No overt Cushing features or other secondary cause
Outpatients referred for osteoporosis in Italy, 219 in all, screened for subclinical hypercortisolism rather than overt Cushing syndrome
Subclinical hypercortisolism was found in 10.8% of 65 patients with vertebral fractures and 4.8% of those with osteoporosis (Chiodini 2007).Chiodini 2007 osteoporosis screening study
4.8% to 10.8%
3
Type 2 diabetes with HbA1c above 8%+Overweight+No specific clinical features of Cushing syndrome
Overweight inpatients referred for poorly controlled type 2 diabetes in Bordeaux, France, 200 in all
Definitive occult Cushing syndrome was found in 4 of 200, or 2%, including 3 with Cushing disease (Catargi 2003).Catargi 2003 diabetes screening study
2%

How often diagnosed patients show it

Share of patients already diagnosed who had the finding, in the group named on each row. Groups differ by age and type, so read each row with its group.

1
Hypertension+Several other clinical signs, on average 5 of 11
Patients with overt Cushing syndrome in the German Cushing registry, 129 in all and 85 of them pituitary
Hypertension was the most common comorbidity, in 78% to 92% across subtypes, yet 28% had only 0 to 3 signs (Braun 2024).German Cushing registry phenotype study
78% to 92%

Also described, without a comparable figure

Type 2 diabetes with HbA1c 7.5% to 11.5% + 2 or more glucose-lowering medicines: Post-DST cortisol stayed above 1.8µg/dL in 23.8%, and in 36.6% of those taking 3 or more blood pressure drugs (Buse 2025).CATALYST study
Easy bruising + Facial plethora + Proximal muscle weakness + Reddish purple striae over 1cm wide: No frequency for this combination was found; the Endocrine Society lists these as the features that best discriminate Cushing syndrome.Endocrine Society guideline

These figures describe published study groups. They are not the chance that any one patient has Cushing disease, and bars whose ranges overlap are not in a settled order.

Red flags for Cushing disease

What the cited sources describe, grouped by life stage and organ. Each line links to its source.

Signs that best discriminate

Easy bruising, facial plethora, proximal myopathy and striae, especially reddish purple and over 1cm wide, best discriminate Cushing syndrome, per the Endocrine Society.Endocrine Society guideline
The same guideline notes that most of these discriminating features do not have a high sensitivity on their own.Endocrine Society guideline
Bruising with no obvious trauma and unexplained osteoporosis are also named among the more discriminatory features of Cushing syndrome.Endocrine Society guideline
Cushing syndrome is more likely when many signs are present, and accumulating new features over time increases the probability further.Endocrine Society guideline
The Endocrine Society says reviewing old photographs of the patient may help show whether physical changes have occurred over time.Endocrine Society guideline

Common features that overlap

Obesity, depression, diabetes, hypertension and menstrual irregularity can all be caused by cortisol excess, yet are common in the general population.Endocrine Society guideline
The Endocrine Society recommends testing patients with features unusual for their age, such as osteoporosis or hypertension.Endocrine Society guideline
Hypertension was the most common comorbidity at diagnosis in the German Cushing registry, found in 78% to 92% across subtypes.German Cushing registry phenotype study
Hypokalemia, kidney stones, unusual infections and polycystic ovary syndrome are listed by the Endocrine Society as overlapping conditions.Endocrine Society guideline
In the European registry, men had more vertebral fractures than women, at 52% against 18% of patients.European Registry on Cushing's syndrome

Children and teens

The Endocrine Society recommends testing children with a decreasing height percentile and increasing weight.Endocrine Society guideline
The Pituitary Society calls lack of height gain with weight gain the most common presentation of Cushing syndrome in children.Pituitary Society 2021 consensus
In children over age 6, Cushing disease is the most common cause, while adrenal causes are more common in younger children.Pituitary Society 2021 consensus
The Endocrine Society says testing is not indicated in obese children unless their statural growth rate has slowed.Endocrine Society guideline

Adrenal and familial settings

The Endocrine Society also recommends testing patients with an adrenal incidentaloma compatible with an adenoma for Cushing syndrome.Endocrine Society guideline
People with Carney complex or multiple endocrine neoplasia type 1 should be evaluated by an endocrinologist within a surveillance screening program.Endocrine Society guideline

Cushing disease is often mistaken for

Diagnoses patients commonly carry first, and why the sources say they are confused.

First diagnosis	Why it is confused
Obesity or the metabolic syndrome	A meta-analysis of 5367 patients notes that Cushing features overlap with metabolic syndrome, obesity, osteoporosis and depression, so diagnosis can take years.Time to diagnosis meta-analysis
Type 2 diabetes alone	A meta-analysis of 14 studies found Cushing syndrome in a pooled 1.4% and any endogenous hypercortisolism in 3.4% of patients with type 2 diabetes.Type 2 diabetes meta-analysis
Essential hypertension	Screening studies cited by the Endocrine Society found Cushing syndrome in 0.5% to 1% of patients with hypertension.Endocrine Society guideline
Age-related osteoporosis	The Endocrine Society cites unsuspected Cushing syndrome in as many as 10.8% of older patients with osteoporosis and vertebral fracture.Endocrine Society guideline
Depression or another psychiatric disorder	Depression, anxiety and obsessive-compulsive disorder can cause mild hypercortisolism with abnormal dexamethasone suppression and mildly raised urine cortisol.Endocrine Society guideline
Polycystic ovary syndrome	The Pituitary Society lists polycystic ovary syndrome among conditions that activate the HPA axis and can give abnormal screening results.Pituitary Society 2021 consensus
Alcohol-related pseudo-Cushing state	Alcohol dependence can cause features and test results suggestive of Cushing syndrome without true disease, according to the Endocrine Society.Endocrine Society guideline
Iatrogenic Cushing syndrome from glucocorticoids	The Endocrine Society calls prescribed corticosteroids the most common cause of Cushing syndrome, and it recommends a drug history before testing.Endocrine Society guideline
Mild autonomous cortisol secretion	In the German Cushing registry, symptoms and clinical signs overlapped between overt Cushing syndrome and mild autonomous cortisol secretion.German Cushing registry phenotype study

Codes patients often carry before this diagnosis

For spotting the pattern in a problem list or registry. Descriptions are checked daily against NLM's ICD-10-CM service; this is not coding advice.

Type 2 diabetes mellitus, with hyperglycemia or without complications E11.65, E11.9

A meta-analysis found Cushing syndrome in a pooled 1.4% of patients with type 2 diabetes across 14 studies.Type 2 diabetes meta-analysis

Essential or resistant hypertension I10, I1A.0

The Endocrine Society names hypertension that is unusual for the patient's age as a reason to test for Cushing syndrome.Endocrine Society guideline

Osteoporosis, or osteoporosis with vertebral fracture M81.0, M80.08XA

Unsuspected Cushing syndrome was found in as many as 10.8% of older patients with osteoporosis and vertebral fracture.Endocrine Society guideline

Spontaneous ecchymoses, striae or muscle weakness R23.3, L90.6, M62.81

Easy bruising, striae and proximal muscle weakness are among the features that best discriminate Cushing syndrome.Endocrine Society guideline

Obesity or abnormal weight gain E66.9, R63.5

Obesity and weight gain overlap with Cushing syndrome and can delay its diagnosis for years, per a large meta-analysis.Time to diagnosis meta-analysis

Polycystic ovary syndrome, hirsutism or irregular menstruation E28.2, L68.0, N92.6

The Endocrine Society lists polycystic ovary syndrome, hirsutism and menstrual abnormalities among features that overlap with Cushing syndrome.Endocrine Society guideline

Depression, unspecified F32.A

Depression is both a common feature of Cushing syndrome and a cause of mild hypercortisolism without true disease.Endocrine Society guideline

Hypokalemia E87.6

The Pituitary Society names profound hypokalemia, with very high UFC, as a pointer toward ectopic ACTH secretion.Pituitary Society 2021 consensus

Drug-induced or alcohol-induced pseudo-Cushing's syndrome E24.2, E24.4

Exogenous glucocorticoids and alcohol dependence both cause features or results that must be separated from endogenous Cushing syndrome.Endocrine Society guideline

Testing for Cushing disease, step by step

The testing order the cited guidance describes, by who it applies to. It summarizes published guidance and is not a plan for any one patient.

Anyone being considered for Cushing syndrome

Drug history before any test
The Endocrine Society recommends a thorough history of oral, rectal, inhaled, topical and injected glucocorticoids first. It warns that skin creams, herbal tonics and joint or nerve injections may be overlooked.Endocrine Society guideline
Other drugs with glucocorticoid activity
The same guideline notes that megestrol acetate has glucocorticoid activity and in high doses may cause Cushing syndrome.Endocrine Society guideline
Start with a high-accuracy test
The Endocrine Society recommends urine free cortisol, late-night salivary cortisol, the 1mg overnight DST or the 48-hour 2mg DST. It says the choice depends on which test suits a given patient.Endocrine Society guideline
The Pituitary Society's starting tests
The 2021 consensus recommends starting with the DST, UFC or late-night salivary cortisol, depending on local availability. It notes that multiple salivary samples may be easier for patients.Pituitary Society 2021 consensus
Collect more than 1 sample
The Endocrine Society recommends at least 2 urine or salivary cortisol measurements, because hypercortisolism can be variable. The 2021 Pituitary Society consensus advises 2 or 3 of either test.Pituitary Society 2021 consensus
Cutoffs in the 2008 guideline
Results suggesting Cushing syndrome are UFC above the assay's normal range, or cortisol above 1.8µg/dL after 1mg dexamethasone. A late-night salivary cortisol above 145ng/dL also suggests the diagnosis, per the same guideline.Endocrine Society guideline
Tests not to use for diagnosis
The Endocrine Society recommends against random serum cortisol or plasma ACTH, urinary 17-ketosteroids and insulin tolerance or loperamide tests. It also excludes imaging and the 8mg DST at this stage.Endocrine Society guideline

Patients with an abnormal or discordant first result

Endocrinologist review and a second test
The Endocrine Society recommends endocrinologist evaluation and another recommended test after any abnormal result. Concordant normal results on 2 different tests end testing unless cyclic disease is suspected.Endocrine Society guideline
Dexamethasone-CRH or midnight serum cortisol
The Endocrine Society suggests these additional tests in specific situations. It suggested against the desmopressin test outside research studies until more data validated it.Endocrine Society guideline
Discordant results
The Endocrine Society suggests further evaluation and follow-up, especially when pretest probability is high. It notes that mild or cyclic disease can give discordant results.Endocrine Society guideline
Suspected pseudo-Cushing state
The Pituitary Society recommends weighing symptom duration and repeating tests, noting most patients have mild hypercortisolism. It describes monitoring for 3 to 6 months to see whether symptoms resolve.Pituitary Society 2021 consensus
Tests that separate pseudo-Cushing
The consensus says the Dex-CRH test, the 2-day low-dose test or the desmopressin test may distinguish ACTH-dependent Cushing syndrome from pseudo-Cushing.Pituitary Society 2021 consensus

Patients with confirmed hypercortisolism

Morning plasma ACTH
A 2026 Korean and Japanese consensus calls morning ACTH useful for separating ACTH-dependent from ACTH-independent disease. It notes overlapping ACTH levels between Cushing disease and adrenal disease limit specificity.Korean and Japanese 2026 consensus

Patients with ACTH-dependent Cushing syndrome

Pituitary MRI
The Pituitary Society calls MRI the imaging method of choice and suggests 3T over 1.5T where available. It adds that about a third of scans in Cushing disease remain negative.Pituitary Society 2021 consensus
CRH or desmopressin stimulation
Rises in ACTH and cortisol after CRH or desmopressin usually indicate Cushing disease, per the consensus. It adds that no test reaches 100% specificity, and results may be discordant.Pituitary Society 2021 consensus
IPSS by pituitary lesion size
The consensus agreed lesions under 6mm should have IPSS, while lesions of 10mm or more with consistent dynamic tests do not need it. Expert opinions differed for 6 to 9mm lesions, but most favored IPSS.Pituitary Society 2021 consensus
How IPSS is done
The consensus says IPSS should preferably be done in a specialized center, with the patient hypercortisolemic at the time. It says IPSS should not be used to diagnose hypercortisolism itself.Pituitary Society 2021 consensus
Suspected ectopic ACTH
When prompt brain MRI is unavailable, the consensus calls thin-slice neck-to-pelvis CT useful if ectopic ACTH is suspected. Its examples are a male patient with very high UFC or profound hypokalemia.Pituitary Society 2021 consensus
Cyclic disease before localization
In a review of 212 cyclic cases, IPSS during hypercortisolism had 100% positive and negative predictive values. Done regardless of cortisol status, they fell to 73% and 86%.Cyclic Cushing syndrome review

Special situations named by the Endocrine Society

Pregnancy
The Endocrine Society recommends UFC and recommends against dexamethasone testing in the initial evaluation of pregnant women.Endocrine Society guideline
Antiepileptic drugs
It recommends against dexamethasone testing with antiepileptic drugs that enhance dexamethasone clearance, measuring nonsuppressed cortisol in blood, saliva or urine instead.Endocrine Society guideline
Severe renal failure
The guideline suggests the 1mg overnight DST rather than UFC for initial testing when renal failure is severe.Endocrine Society guideline
Suspected cyclic or mild disease
It suggests UFC or salivary cortisol rather than DSTs for suspected cyclic disease. For suspected mild disease it suggests the 1mg DST or late-night cortisol.Endocrine Society guideline

Children and adolescents

Testing in children
The Pituitary Society says UFC, late-night salivary cortisol and the 1mg DST are all used in children. It calls the Dex-CRH test not useful and the role of IPSS more limited.Pituitary Society 2021 consensus

Where testing goes wrong

Testing without first excluding exogenous glucocorticoids carries a very large risk of unnecessary testing, according to the Endocrine Society.Endocrine Society guideline
Estrogens raise CBG, and the Endocrine Society reports false-positive overnight DST results in 50% of women taking oral contraceptives.Endocrine Society guideline
UFC measures unbound cortisol, so it stays normal in healthy women whose serum cortisol is raised by oral estrogen, per the Endocrine Society.Endocrine Society guideline
The Pituitary Society says the DST may not be reliable in women treated with oral estrogen, though it may suit shift workers.Pituitary Society 2021 consensus
CYP3A4 inducers such as phenobarbital, carbamazepine and St John's wort can cause false-positive DST results, the Pituitary Society notes.Pituitary Society 2021 consensus
Fluoxetine, cimetidine and diltiazem can slow dexamethasone metabolism and cause false-negative DST results, according to the same consensus.Pituitary Society 2021 consensus
Rapid gut transit, chronic diarrhea or celiac disease can cause false-positive DST results through poor dexamethasone absorption.Pituitary Society 2021 consensus
Measuring dexamethasone alongside cortisol, against laboratory-specific expected values, can reduce the risk of false-positive DST results, the consensus says.Pituitary Society 2021 consensus
A 5µg/dL DST cutoff misclassified up to 15% of patients with Cushing disease as negative, which is why 1.8µg/dL is recommended.Endocrine Society guideline
UFC can be falsely low when creatinine clearance falls below 60mL/min, and it falls further as renal failure worsens.Endocrine Society guideline
High fluid intake of 5 liters a day or more significantly increases UFC, according to the Endocrine Society.Endocrine Society guideline
Random variability between UFC collections can be as high as 50%, so the Pituitary Society advises 2 or 3 collections.Pituitary Society 2021 consensus
Late-night salivary cortisol should not be used in night-shift workers or others whose day and night cycle is disrupted.Pituitary Society 2021 consensus
Licorice, chewing tobacco and smoking may raise late-night salivary cortisol, and steroid lotions or oral gels can contaminate the sample.Endocrine Society guideline
In men aged 60 or older, 20% overall and 40% with diabetes and hypertension had at least 1 raised salivary cortisol.Endocrine Society guideline
Pseudo-Cushing results are usually mild, and the Pituitary Society says UFC is almost always within 3-fold of normal.Pituitary Society 2021 consensus
The Endocrine Society puts the overlap of UFC between pseudo-Cushing states and Cushing syndrome at up to about 4-fold normal.Endocrine Society guideline
Pregnancy, physical stress, malnutrition, intense chronic exercise and hypothalamic amenorrhea can raise cortisol without Cushing syndrome.Endocrine Society guideline
UFC can be normal if urine is collected while cyclic disease is inactive, and in some patients with mild disease.Endocrine Society guideline
In a review of 212 cyclic Cushing syndrome cases, 6% of patients had unnecessary surgery after misclassification.Cyclic Cushing syndrome review
In the German registry, 28% of patients with overt Cushing syndrome had only 0 to 3 of 11 clinical signs.German Cushing registry phenotype study
Upper limits of normal are much lower with HPLC or tandem mass spectrometry than with antibody-based cortisol immunoassays.Endocrine Society guideline

Where to test

Cortisol screening tests through clinical laboratories: UFC, salivary cortisol and dexamethasone suppression tests are run by clinical laboratories, and the Endocrine Society stresses that results differ by assay. Salivary samples stay stable for weeks and can be mailed.Endocrine Society guideline
Dexamethasone level with the overnight DST: The Pituitary Society says measuring a dexamethasone level may help when a false-positive DST is suspected from the clinical scenario.Pituitary Society 2021 consensus
Pituitary MRI and IPSS at a specialized center: The Pituitary Society suggests 3T pituitary MRI where available and says IPSS should preferably be performed in a specialized center because of potential patient risk.Pituitary Society 2021 consensus

Family screening and referral

Who else in the family

The Pituitary Society says corticotroph adenomas are predominantly sporadic, arising from the expansion of a single mutated cell.Pituitary Society 2021 consensus
Patients with familial tumor syndromes such as MEN1, FIPA and DICER1 rarely develop corticotroph adenomas, per the same consensus.Pituitary Society 2021 consensus
In children, germline variants in MEN1, RET, AIP, PRKAR1A, CDKN1B, DICER1, SDHx and CABLES1 may all predispose to Cushing disease.Pituitary Society 2021 consensus
The consensus says genetic screening in children is usually reserved for a family history or other signs of a genetic syndrome.Pituitary Society 2021 consensus
When an underlying genetic syndrome is present, it calls genetic counseling for the child and family members necessary.Pituitary Society 2021 consensus
The Endocrine Society says people with Carney complex or MEN1 should have endocrinologist evaluation as part of a surveillance screening program.Endocrine Society guideline

Who to refer to

The Endocrine Society recommends endocrinologist evaluation for anyone with at least 1 abnormal screening result, to confirm or exclude Cushing syndrome.Endocrine Society guideline
It also recommends endocrinologist review when tests are normal but pretest probability is high, as with suspected cyclic disease.Endocrine Society guideline
The panel observed that referral to endocrinology centers with Cushing syndrome expertise is likely associated with better patient outcomes.Endocrine Society guideline
The Pituitary Society says IPSS should preferably be performed in a specialized center, because of potential risk to the patient.Pituitary Society 2021 consensus
Children with Cushing syndrome should be referred to multidisciplinary centers with pediatric endocrinologists expert in pituitary disorders, per the consensus.Pituitary Society 2021 consensus
The Italian Society of Endocrinology's 2026 position statement directs its screening advice to all health care providers, not only endocrinologists.Italian Society of Endocrinology 2026 position statement

Find a specialist by state

From the CMS NPI Registry, a public directory of US clinicians by registered specialty. A listing is not an endorsement and says nothing about experience with Cushing disease; patient organizations and academic centers can often name experienced clinicians.

ICD-10-CM codes for Cushing disease

For orders, referrals and prior authorization. Each code is checked daily against NLM's ICD-10-CM service.

E24.0Pituitary-dependent Cushing's diseaseCurrent in NLM's ICD-10-CM listNLM ICD-10-CM lookup

E24.9Cushing's syndrome, unspecifiedCurrent in NLM's ICD-10-CM listNLM ICD-10-CM lookup

Once the diagnosis is confirmed

Cushing syndrome (endogenous hypercortisolemia) drugs for prescribers2 prescribing guides, side by side: Isturisa, Recorlev. The page also lists 2 other FDA-approved medicines without a guide yet.Open trialsScreen a de-identified patient against every recruiting Cushing disease study on ClinicalTrials.gov.Patient and family pageThe plain-language Cushing disease page, with trials, treatments and help paying.

For the patient: why your doctor ordered this test

Plain language a patient can read or take home.

Your doctor ordered these tests because some of your signs could mean your body is making too much cortisol, a stress hormone.

Too much cortisol over a long time is called Cushing syndrome. It can cause weight gain, easy bruising, weak muscles and high blood sugar.

When a small growth in the pituitary gland at the base of the brain causes it, doctors call it Cushing disease.

Steroid medicines, including creams, inhalers and joint shots, can cause the same signs, so your doctor will ask about every medicine you use.

The first tests measure cortisol in your urine over 24 hours, in saliva late at night, or in blood after a bedtime dexamethasone pill.

Most people need more than 1 test, and some are repeated, because cortisol levels can go up and down from day to day.

Birth control pills with estrogen, some seizure medicines and night shift work can change some results, so tell your doctor about them.

If the tests confirm too much cortisol, more blood tests and an MRI scan help find where it is coming from.

Questions clinicians ask about Cushing disease testing

Which combinations of findings should prompt testing for Cushing disease?

In published screening and biopsy studies, the highest yields came from resistant hypertension (8% of patients with resistant hypertension in Brazil, 423 in all, screened for subclinical hypercortisolism; none had overt Cushing syndrome), and from osteoporosis with a T-score of -2.5 or lower plus vertebral fractures (4.8% to 10.8% of outpatients referred for osteoporosis in Italy, 219 in all, screened for subclinical hypercortisolism rather than overt Cushing syndrome). Among patients already diagnosed, the most common combination began with hypertension, seen in 78% to 92% of patients with overt Cushing syndrome in the German Cushing registry, 129 in all and 85 of them pituitary. These figures describe study groups, not any one patient's chance of having Cushing disease.

What is the first test for suspected Cushing syndrome?

The 2008 Endocrine Society guideline recommends 1 of 4 tests: urine free cortisol, late-night salivary cortisol, the 1mg overnight DST or the 48-hour 2mg DST. The 2021 Pituitary Society consensus recommends starting with the DST, UFC or salivary cortisol, depending on local availability. The Endocrine Society says a thorough glucocorticoid drug history comes before any test.

How many abnormal tests confirm Cushing syndrome?

The Endocrine Society recommends looking for the cause only after concordantly abnormal results on 2 different tests. It asks for at least 2 urine or salivary measurements, and the Pituitary Society advises 2 or 3. Concordant normal results on 2 different tests end testing unless cyclic disease is suspected.

Can oral contraceptives cause a false positive dexamethasone suppression test?

Yes; the Endocrine Society reports false-positive overnight DST results in 50% of women taking oral contraceptives, because estrogen raises CBG and total cortisol. It notes that UFC is not affected by CBG changes. The Pituitary Society says the DST may not be reliable in women treated with oral estrogen.

When is inferior petrosal sinus sampling needed for Cushing disease?

The 2021 Pituitary Society consensus agreed that patients with ACTH-dependent disease and pituitary lesions under 6mm should have IPSS. It found lesions of 10mm or more with consistent dynamic tests do not need it, and most experts favored IPSS for 6 to 9mm. It also says IPSS should not be used to diagnose hypercortisolism itself.

What causes a false positive late-night salivary cortisol?

Night-shift work, depression, smoking, licorice or chewing tobacco and steroid lotions or oral gels are named causes, per the Endocrine Society. It also reports raised results in 20% of men aged 60 or older. The Pituitary Society says the test should not be used in night-shift workers.

Should patients with type 2 diabetes be screened for Cushing syndrome?

The Endocrine Society recommends against widespread testing, and instead tests patients with features unusual for age or multiple progressive features. A 14-study meta-analysis found Cushing syndrome in a pooled 1.4% of patients with type 2 diabetes. Higher figures in some studies count milder hypercortisolism defined by the DST, not overt Cushing syndrome.

What is the ICD-10 code for Cushing disease?

The ICD-10-CM code is E24.0, pituitary-dependent Cushing's disease, per the National Library of Medicine's ICD-10-CM lookup checked November 10, 2026. Cushing's syndrome, unspecified, is E24.9, and ectopic ACTH syndrome is E24.3. Orphanet's cross-referencing maps Cushing disease exactly to ICD-10 code E24.0.

Sources

The Diagnosis of Cushing's Syndrome: An Endocrine Society Clinical Practice Guideline. Journal of Clinical Endocrinology and Metabolism 2008;93(5):1526-1540 (Nieman LK et al; co-sponsored by the European Society of Endocrinology; the task force received no corporate funding), via Oxford Academic, 2008-05.
Consensus on diagnosis and management of Cushing's disease: a guideline update. Lancet Diabetes and Endocrinology 2021;9(12):847-875 (Fleseriu M, Biller BMK et al for the Pituitary Society; meeting logistics funded by unrestricted grants from Ascendis, Crinetics, HRA Pharma, Novo Nordisk, Recordati Rare Diseases and Strongbridge; many authors report industry ties), via PubMed Central author manuscript, 2021-10-20.
Consensus on the diagnosis of Cushing's disease: a collaborative statement from the Korean Endocrine Society and Japan Endocrine Society. Endocrine Journal 2026;73(2):355-366 (Lee J, Fukuoka H et al; no funding and no conflicts declared; also published in Endocrinology and Metabolism), via PubMed Central, 2026-01-23.
Who and how to screen for Cushing's syndrome: the position statement of the Italian Society of Endocrinology. Journal of Endocrinological Investigation 2026;49(3):461-481 (Ceccato F et al; no conflicts declared), via PubMed abstract, 2025-12-09.
The European Registry on Cushing's syndrome: 2-year experience. Baseline demographic and clinical characteristics. European Journal of Endocrinology 2011;165(3):383-392 (Valassi E et al for the ERCUSYN Study Group), via PubMed abstract; funding and disclosures not seen, 2011-06-29.
Time to Diagnosis in Cushing's Syndrome: A Meta-Analysis Based on 5367 Patients. Journal of Clinical Endocrinology and Metabolism 2020;105(3):dgz136 (Rubinstein G et al), via PubMed abstract; funding and disclosures not seen, 2020-03-01.
Frequency of clinical signs in patients with Cushing's syndrome and mild autonomous cortisol secretion: overlap is common. European Journal of Endocrinology 2024 (Braun LT et al, German Cushing's registry; no conflicts declared apart from an editorial role), via PubMed abstract, 2024-09-30.
Prevalence of hypercortisolism in type 2 diabetes patients: a systematic review and meta-analysis. European Journal of Endocrinology 2016;175(6):R247-R253 (Steffensen C et al), via PubMed abstract; funding and disclosures not seen, 2016-06-27.
Diagnostic challenges in cyclic Cushing's syndrome: a systematic review. Lancet Diabetes and Endocrinology 2023;11(8):593-606 (Nowak E, Reincke M et al; no competing interests declared), via PubMed abstract, 2023-07-07.
ICD-10-CM search results for "cushing" (Clinical Table Search Service). National Library of Medicine, 2026-11-10.
Occult Cushing's syndrome in type-2 diabetes. Journal of Clinical Endocrinology and Metabolism 2003;88(12):5808-5813 (Catargi B, Tabarin A et al), via PubMed abstract; funding and disclosures not seen, 2003-12.
Prevalence of Hypercortisolism in Difficult-to-Control Type 2 Diabetes. Diabetes Care 2025;48(12):2012-2020 (Buse JB, Kahn SE et al for the CATALYST investigators; funded by Corcept Therapeutics, 3 authors are Corcept employees), via PubMed Central, 2025-04-18.
Subclinical hypercortisolism among outpatients referred for osteoporosis. Annals of Internal Medicine 2007;147(8):541-548 (Chiodini I et al), via PubMed abstract; funding and disclosures not seen, 2007-10-16.
Prevalence and associated factors of subclinical hypercortisolism in patients with resistant hypertension. Journal of Hypertension 2012;30(5):967-973 (Martins LC et al), via PubMed abstract; funding and disclosures not seen, 2012-05.

A reference for licensed professionals, checked against its sources on November 10, 2026. It summarizes what the cited guidance says and does not tell anyone how to diagnose or treat a specific patient. Guidelines change; the current guideline and the treating clinician's judgment govern. Trial Friend is an independent information service, not a medical provider.