Determining the normal cut-off levels for hyperandrogenemia in Chinese women of reproductive age.

Objective: To determine the normative cut-off levels of free testosterone (FT), dehydroepiandrosterone sulfate (DHEAS) and total testosterone (TT) among reproductive age women in China.

Study Design: A total of 450 reference subjects without known factors affecting androgen levels were selected from a total study population of 904 presumably healthy women undergoing annual check-ups. The upper limits of normal levels of biochemical androgens were computed by k-means cluster analysis, with the results categorized by age and expressed as both concentrations and percentiles.

Results: The upper limits (cut-off levels) of normal FT, DHEAS and TT levels as determined by k-means cluster analysis are 26 pmol/L, 4.92 μmol/L and 2.39 nmol/L, respectively, in the selected reference subjects. The corresponding percentiles of the cut-off levels of FT (91.8th vs. 87.9th), DHEAS (69.8th vs. 67.6th) and TT (90.0 th vs. 83.8th) were all higher in the reference subjects than in the total study population, suggesting that there were fewer abnormal subjects with elevated androgens in the healthier reference population than in the total study population. The level of DHEAS significantly declined by age (P < 0.05), whereas there was no significant difference in the mean FT or TT levels between age groups among these women of reproductive age.

Conclusions: The normal hyperandrogenism cut-off values for FT, DHEAS and TT are 26.00 pmol/L, 4.92 μmol/L and 2.39 nmol/L, respectively, among women of reproductive age in China who are without factors that might affect androgen levels. The cut-off levels in percentiles are 91.8th for FT, 69.8th for DHEAS and 90.0 th for TT.