Hormones and hair patterning in men: A role for insulin-like growth factor1?

Background: Androgens are important in hair growth and patterning, whereas growth hormone substitution enhances their effect in growth hormone-deficie nt men. No previous study has jointly evaluated the function of sex steroid s, sex hormone-binding globulin (SHBG), and insulin-like growth factor (IGF -1) in determining hair patterning in men. Objective: Ne assessed the relationship between circulating hormone measure ments and both head and chest hair patterning in a sample of elderly men. Methods: Fifty-one apparently healthy men older than 65 years of age were s tudied cross-sectionally. Head and chest hair patterning was assessed by a trained interviewer. Morning blood samples from all subjects were used for measurements of testosterone, estradiol, dehydroepiandrosterone sulfate, SH BG, and IGF-1. Results: Results were obtained from logistic regression models, adjusting s imultaneously for all the measured hormones and age. Men with higher levels of testosterone were more likely to have vertex baldness (odds ratio [OR] = 2.5, 95% confidence interval [CI: 0.9 to 7.8] per 194 ng/dL increment of testosterone). In addition, for each 59 ng/mL increase in IGF-1, the odds o f having vertex baldness doubled (95% CI [1.0 to 4.6]). Those who were foun d to have higher circulating levels of SHBG were less likely to have dense hair on their chest (OR = 0.4, 95% CI [0.1 to 0.9] per 24 nmol/L increment in SHBG]). Conclusion: Testosterone, SHBG, and IGF-1 may be important in determining h air patterning in men.