Treatment of menstrual irregularities with dexamethasone in congenital adrenal hyperplasia

Abnormal menstrual patterns occur frequently in adolescent girls with congenital adrenal hyperplasia (CAH). In this report, two sisters with CAH secondary to the 21-hydroxylase defect are described in whom the administration of dexamethasone, a long-acting glucocorticoid, initiated or regulated their menstrual cycles. Plasma levels of 17-hydroxyprogesterone and androstenedione were elevated while on therapy with 80 mg/day of hydrocortisone, and became normal after treatment with daily dexamethasone, 1.5 mg. Urinary excretion of 17-ketosteroids and pregnanetriol showed a similar pattern. Plasma steroid levels remained suppressed after lowering ther dexamethasone dose to 0.75 mg daily, an amount equivalent to less than the original hydrocortisone dose. These data suggest that dexamethasone has a potential role in the management of patients with CAH who have menstrual irregularities, particularly if conventional therapy does not suppress adrenal steroid production.