Neonatal screening for congenital adrenal hyperplasia using a microfilter paper method for 17-alpha-hydroxyprogesterone radioimmunoassay. Experience gained from the study of 22,233 cases.

We examined 22,233 infants born in Emilia-Romagna (Italy). Capillary blood samples for 17-OH-progesterone assay were collected on the 3rd, 4th, 5th, 6th or 7th day of life on filter paper of the same type used for the screening of aminoacidopathy and hypothyroidism. 17-OH-progesterone values were determined using a micromethod modified from that of Pang and co-workers. 20 pg/disk was considered as a threshold value and called for a second assay, which was performed in 0.18% of the cases. Pathologic values of 17-OH-progesterone were confirmed in the serum of 4 neonates. In our population the incidence of 21-hydroxylase deficiency was found to be 1 out of 5,558 cases.