A Rapid Method for the Assay of Plasma Estriol in Pregnancy1

Abstract

A method has been developed for the determination of plasma estriol in the 2nd half of pregnancy. Only 1 ml of plasma per analysis is required and 5 determinations in duplicate can be completed in 5-6 hr. Besides passing the usual tests of precision, sensitivity, reproducibllity and specificity, accurate values are attainable because each determination is corrected for methodological losses by the isotope technique. Values at term in 34 normal pregnancies ranged from 9.3 to 56 [mu]g/100 ml with a mean of 27 and a median of 25. In normal pregnancy the estriol levels rise regularly as pregnancy progresses, increasing about 5-fold in the 3rd trimester. A rapid fall off in the early post-partum period (1-2 hr.) to values one half those obtained just prior to delivery was observed. Glucose, up to 600 mg/100 ml, does not interfere with the analysis.