Androgenetic alopecia in men: Pathogenesis, clinical features, and diagnosis
- Jeff Donovan, MD, PhD
Jeff Donovan, MD, PhD
- Assistant Professor of Medicine
- University of Toronto
- Beth G Goldstein, MD
Beth G Goldstein, MD
- Adjunct Clinical Assistant Professor
- Department of Dermatology
- University of North Carolina at Chapel Hill
- Adam O Goldstein, MD, MPH
Adam O Goldstein, MD, MPH
- Department of Family Medicine
- University of North Carolina at Chapel Hill
Androgenetic alopecia is the most common type of hair loss in men, and affects approximately 50 percent of Caucasian men by age 50. The condition is characterized by the progressive loss of terminal hairs on the scalp in a characteristic distribution. The anterior scalp, mid scalp, temporal scalp, and vertex of the scalp are typical sites of involvement (picture 1A-D). "Male balding" and "male pattern hair loss" are additional terms used to refer to this condition.
The pathogenesis, clinical features, and diagnosis of androgenetic alopecia in men will be reviewed here. Other causes of nonscarring alopecia and the treatment of androgenetic alopecia are discussed separately. (See "Clinical manifestations and diagnosis of alopecia areata" and "Treatment of androgenetic alopecia in men" and "Evaluation and diagnosis of hair loss".)
HAIR GROWTH CYCLE
In order to understand the pathophysiologic changes that occur during the progressive course of androgenetic alopecia, basic knowledge of the normal hair growth cycle is necessary. In humans, all terminal hair follicles are present at birth, and follicular growth occurs in cyclical manner. The growth cycle for follicles on the scalp consists of three main phases [1,2]:
●The growth phase, termed anagen, lasts two to six years . The duration of this phase determines the hair length.
●The involutional phase, termed catagen, lasts two to three weeks.
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- HAIR GROWTH CYCLE
- CLINICAL FEATURES
- Clinical assessment
- Differential diagnosis
- - Diffuse alopecia areata
- - Telogen effluvium
- COMORBID DISEASE
- Cardiovascular disease
- Prostate cancer
- Colon cancer
- INFORMATION FOR PATIENTS
- SUMMARY AND RECOMMENDATIONS