Male pattern baldness is the most common type of hair loss in men. It usually follows a typical pattern of receding hairline and hair thinning on the crown, and is caused by hormones and genetic predisposition.

Alopecia in men; Baldness - male; Hair loss in men; Androgenetic alopecia

Hair grows about an inch every couple of months. Each hair grows for 2 to 6 years, remains at that length for a short period, then falls out. A new hair soon begins growing in its place. At any one time, about 85% of the hair on your head is in the growing phase and 15% is not.

Each hair sits in a cavity in the skin called a follicle. Baldness in men occurs when the follicle shrinks over time, resulting in shorter and finer hair. The end result is a very small follicle with no hair inside. Ordinarily, hair should grow back. However, in men who are balding, the follicle fails to grow a new hair. Why this occurs is not well understood, but it is related to your genes and male sex hormones. Even though the follicles are small, they remain alive, suggesting the possibility of new growth.

The typical pattern of male baldness begins at the hairline. The hairline gradually recedes to form an "M" shape. The existing hair may become finer and shorter. The hair at the crown also begins to thin. Eventually the top of the hairline meets the thinned crown, leaving a horseshoe pattern of hair around the sides of the head.

Hair loss in patches, diffuse shedding of hair, breaking of hair shafts, or hair loss associated with redness, scaling, pain, or rapid progression could be caused by other conditions.

Classic male pattern baldness is usually diagnosed based on the appearance and pattern of the hair loss. Any atypical hair loss may be caused by other medical disorders. A skin biopsy or other procedures may be needed to diagnose other disorders that cause loss of hair.

Hair analysis is not accurate for diagnosing nutritional or similar causes of hair loss. However, it may reveal substances such as arsenic or lead.