PROGESTERONE IN BLOOD

Abstract

SUMMARY A method is described for the chemical determination of progesterone in the peripheral venous blood of women, horses, cattle, sheep and pigs. The recovery rate of progesterone added to human plasma is 73 ± 4% (s.e.); in the cow, the recovery rate is 63 ± 1·9% (s.e.). In pregnant women approximately 25 ml. of plasma is sufficient for an assay, but in domestic animals the blood concentration of progesterone is much lower and a 500 ml. sample of plasma is usually required. The method has been used for the determination of blood progesterone levels in both pregnant and non-pregnant domestic animals. In women progesterone has been detected as early as the 10th week of pregnancy, and preliminary results in pregnant cattle are given in the following paper [Short, 1958]. In addition, the method allows the simultaneous determination of two other related compounds found in peripheral blood: 20α- and 20β-hydroxypregn-4-en-3one. The method is suitable for routine laboratory determinations; results can be obtained within 24 hr of receipt of a blood sample, and it is possible to carry out a number of assays in 1 day. If small amounts of progesterone are incubated with whole ox blood at 37° C, there is a slow transformation (half-life approximately 7 hr) to 20β-hydroxypregn-4-en-3one.