Obesity regulates bioavailable testosterone levels in women with or without polycystic ovary syndrome

Objective: To evaluate [1] the effects of levels of sex hormone-binding glo bulin (SHBG), albumin, and total testosterone on the distribution of testos terone between SHBG-bound and non-SHBG-bound fractions; [2] the independent effects of polycystic ovary syndrome (PCOS) and body mass index on serum l evels of total testosterone, non-SHBG-bound testosterone, SHBG, and albumin ; and [3] the usefulness of levels of total testosterone and non-SHBG-bound testosterone and of the for androgen index in the diagnosis of PCOS. Design: Retrospective clinical study. Setting: An academic research environment. Patient(s): Forty-three women with oligomenorrhea and PCOS. Twenty-five wom en with regular menstrual cycles and without hirsutism served as controls. Intervention(s): None. Main Outcome Measure(s): Levels of non-SHBG-bound testosterone, total testo sterone, SHBG, and albumin in serum. Result(s): Levels of total testosterone and non-SHBG-bound testosterone, an d the free androgen index were higher in patients with PCOS than in healthy controls. PCOS did not have an effect on the levels of SHBG or albumin, or on the percentage of non-SHBG-bound testosterone. Levels of SHBG and album in were inversely related to body mass index. The percentage and concentrat ion of non-SHBG-bound testosterone and the free androgen index were directl y related to body mass index. Hirsutism did not have an effect on any outco me measure. Conclusion(s): The distribution of total testosterone into SHBG-bound and n on-SHBG-bound fractions is associated with body mass index, not with PCOS. The high levels of non-SHBG-bound testosterone and the high free androgen i ndex in patients with PCOS reflect mainly high levels of total testosterone . Thus, the measurement of levels of non-SHBG-bound testosterone and the ca lculation of the free androgen index provide no further information in the diagnosis of PCOS beyond that provided by the measurement of levels of tota l testosterone. (Fertil Steril(R) 1999;71:457-61. (C)1999 by American Socie ty for Reproductive Medicine.).