Monitoring congenital adrenal hyperplasia using blood spot 17-hydroxyprogesterone assay

Blood spots taken by finger prick collected on filter paper cards can provide an option to venous blood extraction in monitoring 17-OHP levels in children with Congenital Adrenal Hyperplasia (CAH). This study was done to evaluate the usefulness of blood spot 17-OHP in monitoring disease control in pre-pubertal children with CAH, to correlate it with simultaneously extracted venous 17-OHP levels, and to compare blood spot levels of children with CAH with that of normal non-virilized children. Nine pre-pubertal children with CAH (1 male; 8 females) were enrolled in the study. Age, sex, growth velocity, height age and bone age were determined. Simultaneous venous and blood spot specimens were taken between 0800 and 0900 hours. Nine pre-pubertal, age- and sex-matched normal non-virilized children served as controls. COAT-A-COUNT was used to measure venous 17-OHP levels, and AutoDELFIA Neonatal 17alpha-OH-progesterone was employed for blood spot specimens. Mean age of patients with CAH was 42.78 months (SD= 21.45214). Four had simple virilizing form and five were salt-losers. Venous 17-OHP levels ranged from 7.5 to 800nmol/l. Blood spot 17-OHP levels ranged from < or =0.5000nmol/l to 355.5nmol/l. There was a strong positive correlation between the venous and blood spot determination, with a correlation coefficient gamma= 0.947 (p < 0.001). All of the children in the control group had a blood spot 17-OHP level < or =0.5000nmol/l. Taking blood spot 17-hydroxyprogesterone levels is a simple, acceptable, convenient, and less costly alternative to venous 17-OHP determination in monitoring treatment response of children with CAH. The decision to make treatment modification, however, should be made on random blood spot 17-OHP interpretation in conjunction with clinical history and evaluation of growth parameters.