[Neonatal mass-screening for congenital adrenal hyperplasia due to 21-hydroxylase deficiency. I. Microfilter paper methods for radioimmunoassay of 17 alpha-hydroxyprogesterone].

In order to perform neonatal mass-screening for 21-hydroxylase deficiency (21-OHD), two simplified radioimmunoassay (RIA) methods to estimate 17 alpha-hydroxyprogesterone (17-OHP) were devised, using discs 3 mm in diameter cut from filter paper impregnated with whole blood. One was a direct method to use assay buffer eluent as a sample, and the other was an extraction method to use diethyl ether extract. One disc in the direct method and one-fourth to four discs in the extraction method were used. We used [1, 2, 6, 7-3H(N)]-17-OHP as a tracer, anti-17-OHP-3-carboxymethyloxime-BSA serum as an antiserum and saturated ammonium sulfate to separate the bound from free 17-OHP. The specificity of the antiserum was nearly satisfactory, except for an unnegligible cross-reactivity with 17 alpha-hydroxypregnenolone (17-OH-delta 5P). Both methods were practically easy and rapid, and had satisfactory accuracy and precision. A significant correlation (p less than 0.005) was observed between "Disc-17-OHP" values by both methods and plasma 17-OHP concentrations measured by highly specific RIA, although the values obtained by the direct method were significantly higher (p less than 0.005) than plasma 17-OHP concentrations, which presumably resulted from the cross-reactivity of the antiserum with 17-OH-delta 5P-sulfate. "Disc-17-OHP" values of the untreated or poorly controlled patients with 21-OHD were extremely high compared with normal neonates and children. However, as most premature infants also showed high values, the possibility of giving false-positive results had to be considered.(ABSTRACT TRUNCATED AT 250 WORDS)