Hirsutism and virilization

Harrison's Internal Medicine Chapter 50. Hirsutism and Virilization Hirsutism and Virilization: Introduction Hirsutism, defined as excessive male-pattern hair growth, affects approximately 10% of women. It usually represents a variation of normal hair growth, but rarely it is a harbinger of a serious underlying condition. Hirsutism is often idiopathic but may be caused by conditions associated with androgen excess, such as polycystic ovarian syndrome (PCOS) or congenital adrenal hyperplasia (CAH) (Table 50-1).

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The choice of a specific oral contraceptive should be predicated on the progestational component, as progestins vary in their suppressive effect on SHBG levels and in their androgenic potential. Ethynodiol diacetate has relatively low androgenic potential, whereas progestins such as norgestrel and levonorgestrel are particularly androgenic, as judged from their attenuation of the estrogen-induced increase in SHBG. Norgestimate exemplifies the newer generation of progestins that are virtually nonandrogenic.

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Hormonal Evaluation Androgens are secreted by the ovaries and adrenal glands in response to their respective tropic hormones, luteinizing hormone (LH) and adrenocorticotropic hormone (ACTH). The principal circulating steroids involved in the etiology of hirsutism are testosterone, androstenedione, and dehydroepiandrosterone (DHEA) and its sulfated form (DHEAS). The ovaries and adrenal glands normally contribute about equally to testosterone production.

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PCOS is the most common cause of ovarian androgen excess (Chap. 341). However, the increased ratio of LH to follicle-stimulating hormone that is characteristic of carefully studied patients with PCOS is not seen in up to half of these women due to the pulsatility of gonadotropins. If performed, ultrasound shows enlarged ovaries and increased stroma in many women with PCOS. However, polycystic ovaries may also be found in women without clinical or laboratory features of PCOS.

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Hair Follicle Growth and Differentiation Hair can be categorized as either vellus (fine, soft, and not pigmented) or terminal (long, coarse, and pigmented). The number of hair follicles does not change over an individual's lifetime, but the follicle size and type of hair can change in response to numerous factors, particularly androgens. Androgens are necessary for terminal hair and sebaceous gland development and mediate differentiation of pilosebaceous units (PSUs) into either a terminal hair follicle or a sebaceous gland.

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