Hirsutism is a condition seen in women that is associated with development of androgen-dependent terminal hair (coarse, pigmented) following a male-pattern distribution (face, chest, abdomen, back).
Hair in different areas of the body demonstrates varying levels of androgen sensitivity, depending mostly on local sensitivity of androgen receptors and 5-alpha-reductase activity levels. Terminal hair, also known as sexual hair, is dependent on androgens for development and maintenance. [1] Deplewski D, Rosenfield RL. Role of hormones in pilosebaceous unit development. Endocr Rev. 2000 Aug;21(4):363-92. http://edrv.endojournals.org/cgi/content/full/21/4/363 http://www.ncbi.nlm.nih.gov/pubmed/10950157?tool=bestpractice.com Hair response to androgens varies from person to person and includes increase in follicle size, fiber diameter, and the amount of time spent in anagen (the growth-cycle phase of a hair follicle). [2] Rosenfield RL. Clinical practice. Hirsutism. N Engl J Med. 2005 Dec 15;353(24):2578-88. http://www.ncbi.nlm.nih.gov/pubmed/16354894?tool=bestpractice.com [3] Messenger AG. The control of hair growth: an overview. J Invest Dermatol. 1993 Jul;101(suppl 1):4S-9S. http://www.ncbi.nlm.nih.gov/pubmed/8326154?tool=bestpractice.com
Around 70% to 80% of women with androgen excess manifest hirsutism. [4] Azziz R. The evaluation and management of hirsutism. Obstet Gynecol. 2003 May;101(5 Pt 1):995-1007. http://www.ncbi.nlm.nih.gov/pubmed/12738163?tool=bestpractice.com Excessive sexual hair may be accompanied by signs of virilization: male-pattern alopecia, deepening of the voice, clitoromegaly, increased muscle bulk. When present, virilization indicates an underlying condition associated with moderately to severely elevated androgen levels.
The extent of terminal hair varies by ethnic background and the method used to evaluate it. [4] Azziz R. The evaluation and management of hirsutism. Obstet Gynecol. 2003 May;101(5 Pt 1):995-1007. http://www.ncbi.nlm.nih.gov/pubmed/12738163?tool=bestpractice.com Women of Asian ethnicity have less body hair compared with southern European women. Among white and black American women, the prevalence of hirsutism, as assessed by a standard score, is 20%. [5] DeUgarte CM, Woods KS, Bartolucci AA, et al. Degree of facial and body terminal hair growth in unselected black and white women: toward a populational definition of hirsutism. J Clin Endocrinol Metab. 2006 Apr;91(4):1345-50. https://www.doi.org/10.1210/jc.2004-2301 http://www.ncbi.nlm.nih.gov/pubmed/16449347?tool=bestpractice.com