Insulin resistance is associated with hirsutism in unselected reproductive-aged women

Hirsutism affects 5%-10% of reproductive-aged women worldwide and exhibits clinical importance as a cutaneous manifestation of underlying hyperandrogenism. Racial and genetic factors play roles in manifestation of hirsutism, and the prevalence of hirsutism seems to be low in East Asians. However, the reference value of the modified Ferriman-Gallwey (mFG) score to diagnose hirsutism and the prevalence of hirsutism have not been determined in Korean populations to date. We aimed to investigate the distribution of the mFG score and establish its reference value for defining hirsutism and to examine its relationship with metabolic and reproductive traits in reproductive-aged Korean women.

We enrolled 2139 female volunteers of reproductive age (15-39 years). We recorded mFG scores from 0 to 4 on 9 different body locations (upper lip, chin, chest, arm, upper abdomen, lower abdomen, upper back, lower back and thighs). Hirsutism was defined as >95th percentile of mFG score. In addition, a 75-g oral glucose tolerance test was performed, and the homoeostasis model assessment of insulin resistance (HOMA-IR) was calculated.

The mFG values of the 50th, 75th, 90th and 95th percentiles were 0, 1, 4 and 6, respectively. Therefore, the mFG score was indicative of hirsutism when the score was 6 or greater, which represents the 95th percentile. In the correlation analysis, total testosterone, free testosterone, fasting plasma insulin and HOMA-IR were positively correlated with mFG score (all Ps <0.05). Multiple linear regression analysis revealed that HOMA-IR (β = 0.081) was positively associated with mFG score after adjustments for age, body mass index, total testosterone and the number of menses per year (P < 0.001).

In conclusion, setting the 95th percentile of the mFG score as normal, the reference value to define hirsutism was 6 in reproductive-aged Korean women. HOMA-IR was positively associated with the mFG score even after adjustment for biochemical hyperandrogenism.