Longitudinal study of maternal plasma bioavailable testosterone and androstanediol glucuronide levels during pregnancy

Abstract

Summary: OBJECTIVE The aim of this study to evaluate during normal pregnancy plasma bioavailable testosterone and androstanediol glucuronide levels. MEASUREMENTS Bioavailable testosterone, androstanediol glucuronide and SHBG levels were evaluated every 4 weeks from week 6 to week 38 in 10 normal pregnant women. We also measured plasma oestradiol, oestriol, Δ 4‐androstenedione, 17‐hydroxyprogesterone, progesterone and testosterone. RESULTS The mean bioavailable testosterone levels were within the range of non‐pregnant women but with an increasing trend until delivery. Androstanediol glucuronide had increased at weeks 6 and 8, decreased at week 14, remained low at week 30, and increased again at week 34. SHBG was significantly correlated with testosterone, oestradiol and oestriol. No correlation could be established between androstanediol glucuronide and any other parameter. DISCUSSION Bioavailable testosterone (non‐SHBG bound testosterone) represents the sum of free testosterone plus albumin bound testosterone. The increase in testosterone concentrations with decreased albumin levels during pregnancy, could suggest reduced metabolic clearance of testosterone throughout pregnancy. No correlation was established between the decrease in androstanediol glucuronide and increase in progesterone, suggesting that the decrease in androstanediol glucuronide is not a consequence of the inhibitory effect of progesterone on 5α‐reductase activity.