What is the primary cause of hirsutism at puberty?

The primary cause of hirsutism at puberty is increased androgen production. During puberty, hormonal changes occur that lead to the increased secretion of androgens, which are male hormones that are also present in females at lower levels. This rise in androgen levels can lead to the development of male-pattern hair growth, typically observed in areas such as the face, chest, and back.

Androgens stimulate hair follicles to produce terminal hair, which is thicker and darker than the vellus hair (the fine, light hair typically found on women's bodies). This is a natural part of sexual maturation, but in some individuals, this heightened androgen sensitivity or elevated levels can result in noticeable hirsutism.

While increased estrogen, genetic factors, and obesity can influence hair growth and overall hormonal balance, they do not primarily drive the specific development of hirsutism during the critical period of puberty, where hormone shifts are most pronounced and impactful.