Twenty years experience in rapid identification of congenital adrenal hyperplasia in Hungary

The aim of this study was to assess the effectivity of the identification of patients with congenital adrenal hyperplasia (CAH) in Hungary in the absence of systematic neonatal screening and to estimate the incidence. Dried blood-spot samples of patients clinically suspected at any age to have CAH were collected between 1978 and 1998 throughout the whole country. 17-Hydroxyprogesterone (17-OHP) was measured by radioimmunoassay. Age-specific cut-offs were used. The effectivity of the system was retrospectively assessed. Additional cases were sought to assess the overall incidence of CAH in Hungary. Among the 1,837 patients investigated, 185 cases of CAH were identified. The overall effectivity was 94.7%. The sensitivity and the specificity were 98.9% and 94.2%, respectively. Salt-wasting (SW) boys were, on average, diagnosed 2 weeks later than SW girls, while both boys and girls with the simple virilising (SV) form were diagnosed at similar ages (2 versus 2.5 years). An additional 19 cases were diagnosed during the study period using other methods (plasma and urinary steroid profiles without blood-spot 17-OHP measurements). The incidence of classical CAH in Hungary was 1:14,300 (CI 95% between 1:12,450 and 1:16,795). Presuming that the incidence of CAH is the same among boys and girls, one can calculate that the diagnosis was missed in 24 boys (2 SW, 22 SV). Conclusion: it is possible to identify the vast majority of classical cases of congenital adrenal hyperplasia without a neonatal mass screening programme. However, a significant number of boys with the simple virilising form missed whereas both salt-wasting boys and girls are diagnosed safely.