A RADIOIMMUNOASSAY OF UNCONJUGATED OESTRADIOL IN URINE

Abstract

ABSTRACT A radioimmunoassay has been developed for the measurement of unconjugated oestradiol in urine. After extracting with ether and purifying by thin layer chromatography, the assay is performed using anti-serum prepared against oestrone-17-oxime-bovine serum albumin conjugate. Dextran-coated charcoal is used to separate free and bound fractions. The measurable range on the standard curve is from 10 to 1000 pg. The blank of the method is 9.7 ± 3.6 pg (sd) and is independent of urine volume. The intra-assay coefficient of variation is 9.5 % and the inter-assay variation is 12.8%. The accuracy and specificity of the method are also satisfactory. During one menstrual cycle, urinary free oestradiol averaged 32 ng/day (n = 9, range 22 to 58) during the follicular phase; 341 ng/day at the mid-cycle peak; and 46 ng/day (n=10, range 12 to 138) during the luteal phase. The oestradiol content of 3 consecutive 24-h urines from a normal man was 4.8 ng/day (2.7 to 7.2).