What is Cushing syndrome?

Medical Advisory BoardAll articles are reviewed for accuracy by our Medical Advisory Board
Educational purpose only • Exercise caution as content is pending human review
Article Review Status
Submitted
Under Review
Approved

Last updated: March 6, 2026 • View editorial policy

Personalize

Help us tailor your experience

Which best describes you? Your choice helps us use language that's most understandable for you.

What is Cushing Syndrome

Cushing syndrome is a serious endocrine disorder caused by chronic, excessive exposure to cortisol—either from exogenous glucocorticoid use (most common) or from endogenous overproduction by adrenal tumors, pituitary tumors (Cushing's disease), or ectopic ACTH-secreting tumors. 1, 2

Definition and Etiology

Cushing syndrome represents a constellation of signs and symptoms resulting from prolonged hypercortisolism. 1 The causes break down into two major categories:

Exogenous causes:

  • Iatrogenic glucocorticoid administration is the most frequent cause overall 3, 2

Endogenous causes (incidence 2-8 per million annually): 2

  • ACTH-dependent (60-70% of endogenous cases): 2
    • Cushing's disease: ACTH-secreting pituitary corticotroph adenoma (most common endogenous cause) 4, 1
    • Ectopic ACTH secretion from non-pituitary tumors 1, 5
  • ACTH-independent (adrenal causes): 1, 5
    • Unilateral or bilateral adrenal tumors producing autonomous cortisol 6, 1

Clinical Presentation

The syndrome presents with a characteristic but variable constellation of features that develop insidiously over years, often delaying diagnosis by several years: 3, 2

Classic physical signs: 7, 2

  • Facial plethora and moon facies
  • Purple abdominal striae (>1 cm wide)
  • Easy bruising and fragile skin
  • Central obesity with dorsocervical ("buffalo hump") and supraclavicular fat pads
  • Proximal muscle weakness and atrophy 7, 8
  • Hirsutism in women

Metabolic and cardiovascular complications (present in >80%): 7, 8

  • Hypertension (occurs in >80% of patients) 7, 9
  • Hyperglycemia and diabetes mellitus 7, 9
  • Dyslipidemia 8
  • Visceral obesity 8
  • Hypokalemia 9

Neuropsychiatric manifestations: 7, 1, 8

  • Mood disorders (depression, mania)
  • Cognitive impairment
  • Menstrual irregularities in women 7, 9

Musculoskeletal complications: 8

  • Osteoporosis and pathologic fractures
  • Myopathy 9

Critical Diagnostic Distinction

Heat intolerance is NOT a feature of Cushing syndrome. 9 When a patient presents with features suggestive of Cushing syndrome plus heat intolerance, palpitations, or paroxysmal symptoms, you must screen for pheochromocytoma using plasma free or urinary fractionated metanephrines (sensitivity 96-100%, specificity 89-98%). 7, 9 Misattributing heat intolerance to Cushing syndrome delays diagnosis of pheochromocytoma, which carries high morbidity and mortality if untreated. 9

Morbidity and Mortality

Cushing syndrome is associated with severe multisystem morbidity and significantly increased mortality: 1, 8

  • Cardiovascular deaths from myocardial infarction, stroke, and cardiac failure are the leading causes of mortality 1, 8
  • Thromboembolic events including pulmonary emboli 1, 8
  • Infections and sepsis due to immunosuppression during active disease 8
  • Suicide related to severe neuropsychiatric complications 8
  • Markedly impaired quality of life that persists even after treatment, particularly in Cushing's disease 4, 1

The duration of hypercortisolism directly correlates with the extent of comorbidities and overall survival, making early diagnosis and prompt treatment essential. 5, 8

Screening and Diagnosis

First-line screening tests (perform at least one, preferably two): 1, 2, 5

  • 24-hour urinary free cortisol measurement
  • Late-night salivary cortisol (11 PM)
  • 1 mg overnight dexamethasone suppression test

After confirming hypercortisolism, measure plasma ACTH to distinguish ACTH-dependent from ACTH-independent causes. 2, 5

Treatment Principles

First-line therapy for all endogenous causes is surgical resection of the cortisol-producing tissue: 6, 1, 2

  • Transsphenoidal resection of pituitary adenoma for Cushing's disease 6
  • Unilateral adrenalectomy for unilateral adrenal adenomas 6, 1
  • Minimally invasive surgery should be performed when feasible 6

Second-line therapies include: 1, 10

  • Adrenal steroidogenesis inhibitors (ketoconazole, osilodrostat, metyrapone, mitotane)
  • Glucocorticoid receptor blockers (mifepristone)
  • Pituitary-targeted drugs for Cushing's disease (pasireotide, cabergoline)
  • Radiation therapy
  • Bilateral adrenalectomy for refractory ACTH-dependent cases

Lifelong monitoring is required after treatment to manage persistent comorbidities and detect recurrence. 3, 11

References

1
Research

Cushing syndrome.

Nature reviews. Disease primers, 2025

3
Research

Cushing's Syndrome: Rapid Evidence Review.

American family physician, 2024

5
Research

Diagnostic workup of Cushing's syndrome.

Journal of neuroendocrinology, 2022

8
Research

Complications of Cushing's syndrome: state of the art.

The lancet. Diabetes & endocrinology, 2016

9
Guideline

Heat Intolerance Distinguishes Pheochromocytoma from Cushing Syndrome

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2026

11
Research

European survey on metabolic and cardiovascular risk in Cushing syndrome.

Journal of endocrinological investigation, 2025

Related Questions

How do you diagnose Cushing syndrome and what criteria apply, especially in a patient receiving long-term prednisone for a leprosy reaction?
In an adolescent with atypical shoulder and lateral abdominal striae, what is the most appropriate next step to determine if they represent Cushing syndrome rather than physiologic adolescent striae?
What is the recommended diagnostic approach for suspected Cushing syndrome?
Can Cushing syndrome cause heat intolerance?
What is the appropriate diagnosis and treatment approach for a patient suspected of having Cushing's syndrome?
What is the recommended treatment for ST-elevation myocardial infarction (STEMI)?
What alternative treatments are available for a patient with bacterial vaginosis who cannot swallow metronidazole tablets?
A 50-year-old woman with stage 1 invasive ductal breast cancer (oncotype 7, no nodal involvement) and recent weight gain presents with intermittent bilateral eyelid and facial fasciculations, occasional leg and lip twitching, and occasional dyspnea but no weakness; could this be ALS or a brain tumor, and what initial workup is recommended?
What are the side effects of excessive vitamin D supplementation?
In a typical adult presenting with mild, non‑specific symptoms such as mild chest discomfort, transient headache, or anxiety and no red‑flag findings, is reassurance alone sufficient?
How many Saxenda (liraglutide) pens should be prescribed for a 28‑day regimen of 0.5 mg daily for 7 days followed by 1.2 mg daily for the remaining 21 days?

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

Have a follow-up question?

Our Medical A.I. is used by practicing medical doctors at top research institutions around the world. Ask any follow up question and get world-class guideline-backed answers instantly.

Ask Question