CUSHING SYNDROME excess corticosteroids The most common cause is iatrogenic administration of exogenous corticosteroids (e.g., prednisone). Approximately 85% of the cases of endogenous Cushing syndrome are due to an ACTH-secreting pituitary adenoma (Cushing disease). Cushing disease and primary adrenal tumors are more common in women in the 20- to 40-year- old age-group. Ectopic ACTH production is more common in men. Clinical Manifestations Corticosteroid excess causes o Weight gain the most common feature, results from the accumulation of adipose tissue in the trunk, face, and cervical spine area Hyperglycemia o glucose intolerance (associated with cortisol-induced insulin resistance) and increased gluconeogenesis by the liver. Muscle wasting causes weakness o A loss of bone matrix leads to osteoporosis and back pain o loss of collagen makes the skin weaker and thinner and more easily bruised. o Catabolic processes lead to a delay in wound healing Irritability, anxiety, euphoria, and occasionally psychosis may also occur. Mineralocorticoid excess may cause hypertension (secondary to fluid retention) Adrenal androgen excess severe acne, virilization in women Menstrual disorders and hirsutism in women feminization in men gynecomastia and impotence in men are seen more commonly in adrenal carcinomas. The first indication of Cushing syndrome may be the clinical presentation , including (1) centripetal (truncal) obesity or generalized obesity (2) “moon face” (fullness of the face) with facial plethora (3) purplish red striae (usually depressed below the skin surface) on the abdomen, breast, or buttocks (4) Hirsutism in women (5) Menstrual disorders in women (6) Hypertension (7) Unexplained hypokalemia Diagnostic Studies
Plasma cortisol (the primary glucocorticoid) levels may be elevated, with loss of diurnal variation. When Cushing syndrome is suspected, a 24-hour urine collection for free cortisol is done. Urine cortisol levels higher than the normal range of 80 to 120 mcg/24 hr indicate Cushing syndrome If results are borderline, a low-dose dexamethasone suppression test is done False-positive results can occur in patients with depression and those taking certain medications, including phenytoin (Dilantin ) and rifampicin (rifampin [Rifadin]) Urine levels of 17-ketosteroids may be elevated. A CT scan and MRI of the pituitary and adrenal glands may be done. Hypokalemia and alkalosis are seen in ectopic ACTH syndrome and adrenal carcinoma. Collaborative Care The primary goal of treatment for Cushing syndrome is to normalize hormone secretion o If the underlying cause is a pituitary adenoma, the standard treatment is surgical removal of the pituitary tumor using the transsphenoidal approach o Adrenalectomy is indicated for Cushing syndrome caused by adrenal tumors or hyperplasia. Occasionally, bilateral adrenalectomy is necessary.
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- Summer '17
- Cortisol, Adrenal insufficiency