The effect of metformin on hirsutism in polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is a common reproductive disorder characterised by insulin resistance and often associated with hirsutism. Insulin sensitising agents, such as metformin, improve both the biochemical and reproductive parameters; however, no study has been designed to specifically assess the effect of metformin on hair growth.

Sixteen women with PCOS and hirsutism were enrolled into a 14 month (two 6 month phases with a 2 month washout) double-blind placebo-controlled cross over study.

Hirsutism was assessed using the Ferriman and Gallwey (F-G) score, patient self-assessment and growth velocity. Weight, height and waist-hip ratio were recorded. Gonadotrophins, androgens, plasma glucose and lipids were also measured.

Ten women completed the full 14 month study. There was a significant improvement in hirsutism at the end of the metformin phase compared with placebo: F-G score 15.8+/-1.4 vs 17.5+/-1.2 (P=0.025) and patient self-assessment 2.4+/-0.1 vs 3.3+/-0.3 (P=0.014). Growth velocity, in millimetres per day at the end of each phase also improved (0.67+/-0.17 vs 0.77+/-0.11; P=0.03). There was a non-significant improvement in both sex hormone binding globulin (SHBG) and free androgen index (FAI), although there was a significant difference between baseline and metformin treatment for SHBG (P=0.023) and FAI (P=0.036). Metformin treatment also reduced weight significantly (91.5+/-7.6 vs 94.0+/-9.8 kg; P=0.009) and led to a significant improvement in cycle frequency (0.53+/-0.12 vs 0.35+/-0.08 cycles per month; P=0.008).

We have demonstrated that metformin treatment in a group of women with PCOS results in a clinically and statistically significant improvement in hair growth compared with placebo.