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

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Abstract
The increase of plasma cortisol (F), androstenedione (A), 17.alpha.-hydroxyprogesterone (17-OH-P) and testosterone (T) was measured after i.v. administration of ACTH in heterozygotes for CAH and in controls under 2 different conditions: ACTH stimulation performed without any particular preparation or 1.5 mg dexamethasone (dex.) given the evening before the ACTH stimulation. Plasma F, A, 17-OH-P and T were measured by specific radioimmunoassays. 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 after ACTH stimulation exceeding the +2 SD limit of the 17-OH-P increase found in controls. The detection of female heterozygotes was considerably improved by dex. administration before testing (test 2). In males, a better identification of heterozygotes was obtained without previous dex. administration. By these tests, 100% of female and 79% of male CAH heterozygotes could be correctly identified. There were no significant differences in the levels of F, A and T between heterozygotes and controls except for decreased T levels [without dex. administration] (2P < 0.01) in most male heterozygotes after ACTH stimulation.