Insulin resistance may influence hirsutism development in women without PCOS
In a large cohort of reproductive-age women without polycystic ovary syndrome, insulin resistance was positively associated with hirsutism, independent of age, BMI, total testosterone and the number of menses per year, study data show.
“Insulin and insulin-like growth factor I stimulated hair follicle growth in a dose-dependent manner in an in vitro study,” Do Kyeong Song, MD, PhD, of the department of internal medicine at Ewha Womans University School of Medicine in Seoul, South Korea, and colleagues wrote in the study background. “Moreover, the levels of sex hormone-binding globulin, which modulates the bioavailability of testosterone, are suppressed by hyperinsulinemia secondary to insulin resistance. Therefore, in addition to biochemical hyperandrogenism, [insulin resistance] could contribute to the development of hirsutism.”
Song and colleagues analyzed data from 2,139 Korean women of reproductive age but without PCOS, recruited between December 2008 and October 2010 for a study on the menstrual health of young women. Researchers measured BMI, waist circumference and modified Ferriman-Gallwey score at different body locations, including the upper lip, chin, chest, arm, upper abdomen and thighs (scores range from zero to 9). Hirsutism was defined as the 95th percentile of the modified Ferriman-Gallwey score for the cohort.
Women provided a fasting blood sample during the early follicular phase of the menstrual cycle to assess total testosterone, SHBG and free testosterone, and completed a 75-g oral glucose tolerance test. Researchers also calculated homeostatic model assessment of insulin resistance (HOMA-IR).
Within the cohort, 1,334 women (62.4%) had a modified Ferriman-Gallwey score of zero. Researchers determined that the modified Ferriman-Gallwey score indicative of hirsutism for the cohort was a score of at least 6. Mean Ferriman-Gallwey scores in women with and without hirsutism were 8.7 and 0.7 (P < .0001), respectively.
Compared with women without hirsutism, researchers found that women with hirsutism exhibited increased values of total testosterone (51.5 vs. 47.2 ng/dL), free testosterone (0.48 vs. 0.43 ng/dL), fasting plasma insulin (6.8 vs. 5 mIU/I) and HOMA-IR (1.42 vs. 1.07; P < .05 for all comparisons). Results persisted after adjustment for BMI. Women with hirsutism also had higher levels of 2-hour postload plasma glucose vs. women without hirsutism, with results again persisting after adjustment for BMI (P < .05).
In Spearman’s correlation analyses, total testosterone, free testosterone, fasting plasma insulin, HOMA-IR and number of menses per year were all positively correlated with modified Ferriman-Gallwey score (P < .05 for all comparisons); however, there were no associations between the score and fasting plasma glucose or 2-hour postload plasma glucose level.
In a multivariable regression model, HOMA-IR was positively associated with modified Ferriman-Gallwey score, persisting after adjustment for age, BMI, total testosterone and the number of menses per year (P < .001), according to researchers.
“These findings suggest that HOMA-IR measurement in women with hirsutism may be helpful in early detection of insulin resistance and assessment of risk for metabolic diseases,” the researchers wrote. “Further investigation to determine the optimal [modified Ferriman-Gallwey] reference value for various age groups in a Korean population is needed.” – by Regina Schaffer
Disclosures: The authors report no relevant financial disclosures.