Back
ditki Logo
medical & biological sciences
All Access Pass - 1 FREE Month!
Institutional email required, no credit card necessary.

Cushing's Syndrome for PA

Free One-Month! Institutional (.edu or .org) email required
Log in or start your One-Week Free Trial!
Cushing's Syndrome for the Physician Assistant Licensing Exam
  • Pathophysiology
    • Excess Cortisol Production: Cushing’s syndrome is caused by prolonged exposure to elevated levels of cortisol, leading to systemic effects on metabolism, immune function, and cardiovascular health.
    • ACTH-Dependent vs. ACTH-Independent:
    • ACTH-Dependent: Results from excessive production of adrenocorticotropic hormone (ACTH), which stimulates the adrenal glands to produce cortisol.
    • Cushing's Disease: A pituitary adenoma secreting ACTH is the most common endogenous cause.
    • Ectopic ACTH Production: Non-pituitary tumors (e.g., small-cell lung carcinoma) secrete ACTH.
    • ACTH-Independent: Autonomous cortisol production by the adrenal glands.
    • Adrenal Adenoma/Carcinoma: Adrenal tumors independently secrete cortisol.
    • Exogenous Glucocorticoid Use: The most common cause overall, due to long-term steroid therapy.
  • Clinical Features
    • General Appearance:
    • Central Obesity: Fat deposition in the trunk with relatively thin extremities.
    • Moon Facies: A rounded, full face.
    • Buffalo Hump: Fat accumulation in the upper back.
    • Skin and Hair:
    • Purple Striae: Stretch marks, usually on the abdomen and thighs.
    • Thin Skin and Easy Bruising: Fragile skin with poor wound healing.
    • Hirsutism: Excess hair growth, especially in women.
    • Metabolic and Musculoskeletal:
    • Hyperglycemia: Cortisol increases gluconeogenesis and insulin resistance.
    • Hypertension: Elevated blood pressure due to sodium retention.
    • Osteoporosis: Increased risk of fractures due to decreased bone formation.
    • Proximal Muscle Weakness: Weakness, especially in the thighs and upper arms.
  • Diagnosis
    • 24-Hour Urine Free Cortisol: Measures cortisol levels over 24 hours. Elevated levels confirm hypercortisolism.
    • Late-Night Salivary Cortisol: Cortisol should be low at night; elevated levels suggest Cushing's syndrome.
    • Low-Dose Dexamethasone Suppression Test: Failure to suppress cortisol after dexamethasone indicates Cushing’s syndrome.
    • ACTH Levels: Elevated in ACTH-dependent Cushing’s, low in ACTH-independent causes.
Cortisol test cushings
  • Treatment
    • Surgery:
    • Pituitary Adenoma: Transsphenoidal surgery is the treatment of choice for Cushing’s disease.
    • Adrenal Tumors: Adrenalectomy is indicated for adrenal adenomas or carcinomas.
    • Ectopic ACTH-Producing Tumors: Surgical resection, if feasible.
    • Medical Therapy: Steroidogenesis inhibitors (e.g., ketoconazole) or glucocorticoid receptor antagonists (e.g., mifepristone) for non-surgical candidates.
Key Points
  • Pathophysiology: Cushing's syndrome results from excess cortisol due to pituitary adenomas (Cushing’s disease), adrenal tumors, ectopic ACTH production, or exogenous steroids.
  • Clinical Features: Central obesity, moon facies, purple striae, muscle weakness, hyperglycemia, and hypertension are key findings.
  • Diagnosis: Includes 24-hour urine free cortisol, late-night salivary cortisol, and low-dose dexamethasone suppression test.
  • Treatment: Surgery is the main treatment for pituitary or adrenal tumors; medical management is used when surgery is not an option.

Related Tutorials