Non-chromatographic radiotransinassay for cortisol: application to human adult serum, umbilical cord serum, and amniotic fluid.

Rapid (1-2 hour) non-chromatographic radiotransinassay using horse transcortin can be used to measure cortisol in umbilical cord serum (after hexane-carbon tetrachloride prewash and methylene chloride extraction), in amniotic fluid (after methylene chloride extraction only), and in adult serum (after dilution and boiling without extraction). Since horse transcortin has high affinity (2.4 x 10(9) l/mol) for cortisol, only a few microlitres of sample is required. The assay appears to be highly specific for cortisol clinically except in congenital adrenal hyperplasia.