RADIOIMMUNOASSAY OF OESTRONE AND OESTRADIOL IN HUMAN AND BOVINE PERIPHERAL PLASMA

Abstract

ABSTRACT An antibody against oestradiol-17β-succinyl-bovine-serum-albumin was diluted in a 0.1% phosphate buffer to 1:150 000 without any previous treatment. Sephadex LH-20 columns were used to separate the oestrone and oestradiol fractions. Separation of free from antibody-bound steroids was achieved by a dextrane coated charcoal suspension. Five pg of oestradiol or oestrone was significantly different from 0 in the radioimmunoassay system. The recovery for oestrone and 17β-oestradiol after diethyl ether extraction and column separation was between 87-91 per cent. Highly accurate and precise measurements of both oestrone and 17β-oestradiol were obtained both in women and cows. During pregnancy in the cow oestrone was found to be the predominant free oestrogen in the peripheral plasma and the oestradiol levels were found to be about 10 per cent or less of the oestrone levels. The oestrone levels in the pregnant cow could be measured by a rapid technique omitting the column separation. During the normal menstrual cycle in women the pattern of oestrone and oestradiol closely followed that obtained after ether extraction only. A well defined midcyclic peak of oestrogens was found in all the 34 normal cycles assayed. The increase during the luteal phase was less pronounced.