COMPARISON OF 2 TESTS FOR HETEROZYGOSITY IN CONGENITAL ADRENAL-HYPERPLASIA (CAH)

The increase of plasma cortisol (F), androstenedione (A), 17α-hydroxyprogesterone (17-OH-P) and testosterone (T) was measured after iv administration of ACTH in heterozygotes for CAH and in controls under two different conditions: Test 1: ACTH stimulation was performed without any particular preparation. Test 2: 1,5 mg of dexamethasone (dex) was given the evening before the ACTH stimulation. Plasma F, A, 17-OH-P and T were measured by specific radioimmunoassays (RIA). Following ACTH stimulation, the increase of 17-OH-P was significantly higher in CAH-heterozygotes than in controls in both tests (P<0.0005). Heterozygotes were characterized by a 17-OH-P increase found in controls. The detection of female heterozygotes was considerably improved by the administration of dex. before testing (test 2). In males, however, a better indentification of heterozygotes was obtained without previous administration of dex. (test 1). By these tests, 100% of female (test 2) and 79% of male (test 1) CAH heterozygotes could be correctly indentified. There were no significant differences in the levels of F, A and T between heterozygotes and controls except for decreased T levels in test 1 (2P<0.01) in most male heterozygotes after ACTH stimulation.