Description

• Cushing syndrome is defined as excessive glucocorticoid exposure from exogenous sources (such as steroids) or less commonly from endogenous sources (pituitary, adrenal, pulmonary, etc.).
• The most common cause of endogenous Cushing syndrome is Cushing disease, which is characterized by excessive adrenocorticotropic hormone (ACTH) secretion from a benign pituitary adenoma.
  • Cushing syndrome from excess endogenous sources may also be caused by a benign or malignant nonpituitary corticotropin secreting tumor (known as ectopic Cushing Syndrome).
• System(s) affected: endocrine/metabolic, musculoskeletal, skin/exocrine, cardiovascular and neuropsychiatric

Pediatric Considerations

• Rare in infancy and childhood
• The most common presenting symptom is lack of growth and weight gain.

Pregnancy Considerations
Pregnancy may exacerbate the disease.

Epidemiology

Incidence
The estimated incidence of Cushing syndrome attributable to endogenous production of cortisol ranges from about 2 to 3 per million people annually to 8 per million people annually.

Prevalence

• An estimated 10 to 15 cases per million people are affected yearly.
• Cushing disease most commonly affects adults 20 to 50 years old and is more prevalent in females.
• 2–5% prevalence reported in difficult-to-control diabetics with obesity and hypertension (HTN)

Etiology and Pathophysiology

• Cortisol is a steroid hormone produced by the zona fasciculata of the adrenal cortex. It is classically a catabolic hormone released during periods of stress. Excess levels of cortisol causes increased free glucose, insulin resistance, immunosuppression, neurocognitive changes, bone disorders such as osteoporosis, and mood disorders such as depression and protein catabolism.
• Prolonged glucocorticoid use such as in asthma and COPD is the most common exogenous source.
• Endogenous cause is either ACTH-dependent or ACTH-independent.
  • ACTH is typically secreted by the anterior pituitary gland and stimulates the adrenal glands to release cortisol. As such, release of ACTH from any source will result in increased cortisol levels.

Genetics

• Multiple endocrine neoplasia (MEN) syndrome
• McCune-Albright syndrome (mutation of GNAS1 gene)

Risk Factors

Prolonged use of corticosteroids

General Prevention

Avoid corticosteroid exposure.

Commonly Associated Conditions

Psychiatric disorders, diabetes, HTN, hypokalemia, infections, dyslipidemia, osteoporosis, and poor physical fitness