Analysis of blood spot 17 alpha-hydroxyprogesterone concentration in neonates.

Blood spot 17 alpha-hydroxyprogesterone (17-OHP) concentrations were measured in 515 infants aged from the 4th to the 81st day of life, using a fluorescence enzyme immunoassay method, and the values obtained were analyzed with respect to birth weight, gestational age at birth and sampling age, to obtain accurate reference ranges and to decide appropriate cut-off limits in a neonatal mass screening for steroid 21-hydroxylase deficiency. The results obtained indicate that the blood spot 17-OHP values in neonates should be interpreted using several different reference ranges obtained on the basis of the equivalent age of gestation at blood sampling. In the mass screening, therefore, the cut-off limits for recall are decided by these reference ranges as follows: (1) for blood resampling, 120, 30 and 25 nmol/l for the equivalent sampling ages of 31 weeks or less, 32-41 weeks and 42 weeks or more, respectively, and (2) for rapid confirmation of the disease by means of physical and laboratory examinations, 210, 60 and 60 nmol/l, respectively.