8 Hair follicles and associated glands as androgen targets

The document from 1986 discusses how androgens, particularly testosterone and its derivative 5α-dihydrotestosterone, influence hair growth and sebum secretion. It notes that the response of hair follicles and sebaceous glands to androgens varies by body site and individual. Testosterone is shown to extend the active growth phase of hair follicles and increase hair thickness, growth rate, and pigmentation, especially on the face, trunk, and extremities. The lower pubic triangle can develop without the conversion of testosterone to 5α-dihydrotestosterone, which is necessary in other areas. Sebaceous glands respond to androgens differently, with cell replication and lipid synthesis not uniformly controlled, and may be influenced by pituitary factors such as growth hormone, prolactin, and melanocyte stimulating hormone. The document highlights that the degree of hair growth or sebum secretion may not correlate directly with plasma androgen levels or sex hormone-binding globulin (SHBG) levels, but rather with the sensitivity of the target organ to androgens. Some patients with hirsutism or acne have abnormal androgen or SHBG levels, but many do not, suggesting that peripheral response to androgens is a critical factor in these conditions.