Male pattern hair loss (MPHL) or androgenic alopecia is a hereditary condition that occurs as a result of certain hormones. Up to 70% of men will be affected by hair loss due to genetic factors during their lifetime.
In genetically predisposed individuals, hair follicles in certain areas of the scalp are programmed to become sensitive to changing hormonal activity. A specific enzyme called alpha-5 reductase is responsible for converting the male hormone testosterone into dihydrotestosterone or DHT, which is primarily responsible for patterned hair loss in males. Typically the temples, hairline, top and vertex of the scalp are the regions affected by hair loss. The rim of hair around the back of the scalp contains hormone-resistant hair follicles which are not sensitive to DHT. When transplanted, follicles from this area will not fall out.
Generalized hair loss or thinning in men may be caused by other factors and not respond to conventional treatments for pattern hair loss. Other causes of hair loss in men include:
- Dietary deficiencies
- Medications such as anti-cancer drugs
- Dermatologic conditions