Radioimmunoassay of total urinary estrogens

We describe a radioimmunoassay for total estrogens in urine. Estrogens are extracted by adsorption on XAD-2 resin, eluted with methanol, and acid-hydrolyzed. Estrogens are then determined in a diluted aliquot of the hydrolysate. Within-run coefficients of variation for estriol values between 6.0 and 100 micrograms/L were less than 5%; between-run CV was 19.6% at an estriol concentration of 16.8 microgram/L. A correlation coefficient of 0.96 was found on comparison of the radioimmunoassay (y) with a standard fluorometric assay (x); the regression equation is y = 2.18 x - 6.70 micrograms/L. Determination on pregnancy and non-pregnancy urine can be done within 4 h.