The Application Of Free Testosterone And Free Androgen Index In Clinical Diagnosis Of PCOS

Objective:Polycystic ovary syndrome(PCOS) is the most common endocrine disorder in women. Hyperandrogenaemia is one of the most important characteristics for assessing PCOS. Currently, the laboratory biomarkers, including total testosterone(TT), free testosterone(FT) and free androgen index(FAI), and clinical features, including hirsutism, acne and obesity, are usually used for PCOS diagnosis. In this paper, we aim to evaluate the consistency and accuracy of FT, FAI and TT to diagnose PCOS in Chinese women, and to identify the cut-off value of FT, and to investigate the correlation between FT and hirsutism/acne for assessing PCOS.Methods:According to the Rotterdam diagnostic criteria, 120 women with PCOS as study group and 80 women without PCOS in the control group were selected from the patients in the first affiliated hospital of university of south China. Fasting blood samples were collected from women during 3-5 days of menstrual cycle for detecting serum levels of TT,FT and sex steroid hormone-binding globulin(SHBG). TT and SHBG can be used for calculation of FAI. Ovarian ultrasound, hirsutism, acne and body mass index(BMI) were also used for evaluation of PCOS. Patients were divided into subgroups according to PCOS, hirsutism and acne, respectively. The multiple parameters were compared among different subgroups.The cut-off of FT to diagnose PCOS alone was identified. The correlation between TT and FAI, FT and FAI was investigated.Results:(1) Between the two groups, the levels of TT(P=0.045), FT(P ﹤ 0.001) and FAI(P ﹤ 0.001) was significantly increased in PCOS-negative group. In addition, the significance of FT and FAI was higher than that of TT. Similarly, the level of BMI(P=0.044) but not SHBG(P=0.462) was also significantly different between two groups.(2) In the present study,the accuracy of FT for PCOS diagnosis is 100% when the value of FT is higher than 60.74pg/ml or less than 24.31pg/ml. When the value of FT is between two cut-off values, FT is not suitable for assessing PCOS alone and the accuracy of FT for PCOS diagnosis is 70.83%.(3) FAI was correlated with TT(P=0.015) or FT(P﹤0.001), respectively. Moreover, the correlation between FT and FAI was stronger than that between TT and FAI.(4) Compared to TT and SHBG, the levels of FT(P=0.037) and FAI(P=0.012) were significantly different between hirsutism-positive group and hirsutism-negative group.(5) Compared to TT and SHBG, the levels of FT(P=0.041) and FAI(P=0.039) were significantly different between acne-positive group and acne-negative group.Conclusions:(1) TT、FT and FAI are all suitable for PCOS diagnosis with excellent consistencies. In addition, FT and FAI are better than TT.(2) In the present study,the up-cut-off and down-cut-off values of FT to diagnose PCOS are 60.74 pg/ml and 24.31pg/ml, respectively. FT can be used alone for PCOS diagnosis when the FT values of patients are higher than up-cut-off value or less than down-cut-off value.(3) FAI is correlated with TT or FT, respectively, and the correlation between FT and FAI was better than that between TT and FAI.(4) The results of hirsutism and acne are consistent with that of FT/FAI, which indicated that hirsutism and acne can also be used for PCOS diagnosis.