Pregnenolone Sulfate in Human Pregnancy Plasma¹

Abstract

A double isotope derivative method for the estimation of pregnenolone (3β-hydroxypregn-5-en-20-one) sulfate in plasma is described. Acetic-1-14C-anhydride is used as reagent and 7α-3H-ammonium pregnenolone sulfate as indicator. Multiple chromatographies before and after acetylation and recrystallization to constant 3H/14C are used to achieve purification. The mean recovery of the indicator is 9 ± 4%. The average absolute deviation of paired samples is 1.5 μg/100 ml. Pregnenolone sulfate can be measured in plasma throughout normal pregnancy. Values are as high as reported values for progesterone. A gradient is shown between fetal and maternal compartments (F > M) and between umbilical artery and umbilical vein (A >V).