irect Solid - PhaseRadioimmunoassayfor Screening 1 7 a - - lydroxyprogesteronein Whole - BloodSamplesfrom Newborns

Ye describe a direct, solid-phase AlA for 17a-hydroxyprolesterone (17-OH-P) that we are using to screen neonates Drcongenital adrenal hyperplasla. Phosphate buffer containrg danazol and anti-i 7-OH-P is placed in tubes coated with intibodyto IgG.Thetubesalsocontainstandards, controls, r bloodsamplesonfilterpaperdIscs 3 mm in dIameter. 1251. theled 17-OH-P is added to each tube. The mixture Is ortex-mixedand incubatedovernight. Thefluidanddiscare smoved, the radioactivityremaining in the tubes is counted, nd the amountof 17-OH-P per disc iscalculatedby using a g-Iogit transformation of the standard curve. Results cornare favorablywith those by twoextraction assays.Inter-and itra-assay CVs were <11% and <9%, respectIvely. Sensivity was 2 pg per assaytube. There is no significantcross eactivity with structurallyrelated steroidsat their physiologial concentrations. Analytical recovery of added 17-OH-P veraged 104%. 17-OH-P In whole blood spotted on filter aper is stable for at least six months.