Clinical meaning
Cushing syndrome results from chronic glucocorticoid excess. Exogenous (most common: iatrogenic steroids) or endogenous (ACTH-dependent: pituitary adenoma 70%, ectopic ACTH 15%; ACTH-independent: adrenal adenoma/carcinoma 15%). Screening: 24h urine free cortisol, late-night salivary cortisol, 1mg overnight dexamethasone suppression test. Clinical features: central obesity, moon face, buffalo hump, striae, proximal weakness, glucose intolerance.
Diagnosis & workup
Diagnostics & workup: - PTH with calcium and phosphorus for parathyroid evaluation - Dexamethasone suppression test (1mg overnight) for Cushing screening - Cosyntropin stimulation test for adrenal insufficiency - Plasma metanephrines for pheochromocytoma screening - Thyroid ultrasound for nodule characterization (TI-RADS scoring) - TSH (most sensitive for primary thyroid dysfunction) - Fine needle aspiration biopsy of thyroid nodules (Bethesda classification)
Risk factors: - Medication-induced endocrinopathy (lithium-thyroid, statin-DM) - Prior radiation to head/neck affecting thyroid or pituitary - Iodine deficiency or excess affecting thyroid function - Eating disorders with hypothalamic amenorrhea - Chronic kidney disease affecting calcium-phosphorus-PTH axis - Family history of endocrine disorders (autoimmune thyroid, T2DM) - Pituitary adenoma causing hormonal hypersecretion or deficiency