Serum free testosterone in polycystic ovary syndrome measured with a new reference method.

Objective: To quantify the actual serum free T with a specific new reference method in women with polycystic ovary syndrome (PCOS) and to analyze the effects of serum free T, total T, and the T:sex hormone-binding globulin (SHBG) ratio on the diagnosis of PCOS.

Setting: Outpatient clinic of reproductive endocrinology at Turku University Central Hospital, Turku, Finland.

Patients: Forty-four oligomenorrheic women with PCOS and 26 weight-matched control women with regular menstrual cycles.

Main Outcome Measures: The concentrations of free T, total T, androstenedione (A), LH, FSH, SHBG, and insulin in serum.

Results: The mean concentrations of free T, total T, A, and LH as well as the LH:FSH and T:SHBG ratios were higher, whereas the mean concentrations of FSH was lower in the women with PCOS than in healthy women. No differences were found in the free T, total T, or T:SHBG levels or in the body mass indexes (BMIs) between the hirsute (n=26) and nonhirsute (n = 18) women with PCOS. Both elevated free T concentrations and high T:SHBG ratios were associated with obesity, but serum total T was independent of BMI. The serum free T measurement discriminated PCOS women from controls to a similar extent as total T and T:SHBG ratio as judged by a receiver operating characteristics analysis.

Conclusions: The present data indicate that determination of free T provides little additional information in the diagnosis of hirsutism or PCOS and does not have to be included to the basic evaluation of these patients. Only half of women with PCOS exhibited elevated serum free T concentrations.