Which hormone is predominantly involved in the regulation of hair growth in women?

Testosterone is a key hormone that plays a significant role in the regulation of hair growth in women. Although it is commonly associated with male hair growth patterns, it is important to recognize that women also produce testosterone, albeit in lower levels than men. In women, testosterone contributes to the development of hair in certain areas of the body, such as the axillary (underarm) and pubic regions.

Hair growth regulation is a complex process that involves various hormones, but testosterone notably influences the hair follicles' activity and can lead to increased hair growth or changes in hair patterns when levels fluctuate. For instance, conditions such as polycystic ovary syndrome (PCOS) can result in elevated testosterone levels, which may cause excessive hair growth known as hirsutism.

In contrast, while hormones like insulin, luteinizing hormone, and thyroxine have significant effects on various bodily functions, their direct impact on hair growth is less pronounced compared to testosterone. Insulin mainly regulates blood sugar levels, luteinizing hormone is crucial for ovulation and reproductive functions, and thyroxine is primarily involved in metabolism. Therefore, testosterone's direct action on hair follicles makes it the predominant hormone influencing hair growth in women.