[Diagnosis of late onset congenital adrenal hyperplasia]

Late onset congenital adrenal hyperplasia (LOCAH) is the most common autosomal recessive disorder in the human. The incidence among women suffering from hirsutism and menstrual disorders varies from 1-35%. 21-hydroxylase deficiency is the most common variant of LOCAH. The partial enzymatic defect can be diagnosed only by ACTH stimulation tests, and not from clinical features or basal hormone levels. A variety of methods have been proposed to detect those with deficient 21-hydroxylase activity, all based on measuring steroid precursors above the enzymatic block, before and after ACTH stimulation. In this review we summarize the different methods of diagnosing 21-OH-LOCAH, and compare the incidence of this disturbance in 64 patients with hirsutism and acne, as calculated by the different methods. These 64 young women were examined in our outpatient clinic in the past 5 years, and have undergone ACTH stimulation tests. While an incidence of 5-6% of homozygote 21-OH-LOCAH was found, the incidence of the calculated heterozygote 21-OH-LOCAH varied between 16-48%. The difficulty in diagnosing heterozygote 21-OH-LOCAH is discussed.