Clinical aspects of congenital adrenal hyperplasia due to 21-hydroxylase deficiency

21-hydroxylase deficiency is the cause of one of the most common hereditary diseases - congenital adrenal hyperplasia (CAH). The level of residual activity of 21-hydroxylase determines the clinical form and severity of the course of the disease. The article presents the clinical characteristics of two forms of CAH – salt-wasting and simple virilizing. Objective. To study the clinical aspects of CAH due to 21-hydroxylase deficiency in children. Material and methods. We analyzed 57 archived case histories and 58 extracts from case histories of children from 0 to 18 years old with an established diagnosis of CAH. In general, the sample comprised cases, of which 36 were boys (48%) and 39 (52%) girls. Results and discussion. Of the 75 children with CAH, 43 (57.3%) had a salt-wasting form, 32 (42.7%) had a simple virilizing form. In children with salt-wasting form, the leading clinical manifestation was salt loss syndrome, with simple virilizing - viril syndrome. The average age of diagnosis with salt-wasting form was 1.5 months (from 1 to 2.6 months), with simple virilizing - 3 years (from 1.4 to 4.4 years). Conclusions. According to our data, in Kazakhstan, the salt- wasting form of СAH is diagnosed more often than a simple virilizing form (57.3% / 42.7%). The problems of timely diagnosis of CAH and in the selection of the appropriate passport gender of the child were identified. Keywords: congenital adrenal hyperplasia, 21-hydroxylase deficiency, salt-wasting form, simple virilizing form.