Excretion of Steroid Hormones in Adults: C₁₉ and C₂₁ Steroids in Faeces from Pregnant Women

The C₁₉ and C₂₁ steroids in faeces from pregnant women have been studied by gas chromatography‐mass spectrometry. Over 90% of the steroids identified were unconjugated and had the following general structures: androstane‐3,17‐diol, 3‐hydroxy‐17β‐pregnan‐20‐one, 3‐hydroxy‐17α‐pregnan‐20‐one, 3β‐hydroxy‐5‐pregnen‐20‐one, pregnane‐3,20‐diol, 3,16α‐dihydroxypregnan‐20‐one, 5β‐pregnane‐3α,17α,20α‐triol, pregnane‐3,16α,20‐triol, and 5α‐pregnane‐3,20α,21‐triol. The C₂₁O₂ steroid isomers in the monosulphate and “diconjugate” fractions had the 5α configuration whereas both 5α and 5β isomers were present in the free steroid fraction. The major part of the 5α‐steroids carried a 3β‐hydroxyl group whereas the predominant 5β‐steroids had a 3α‐hydroxyl group. The results suggest that steroids excreted in the bile are modified by hydrolase, oxidoreductase and dehydroxylase activities of the intestinal microorganisms. The amount of steroids in a pooled smaple of faeces from a nine‐month pregnant woman corresponded to a daily excretion of 33 mg. This value indicates that faecal excretion is important in the elimination of steroids in pregnancy.