The average number of strands on the human scalp ranges from 90,000 to 150,000.

This loss is part of the normal cycle of hair growth. If you notice more hair loss than this, see your healthcare provider to find out the cause.

Each strand grows at a rate of about a half-inch a month. After finishing its growth, the strand will rest, then fall out. A new strand begins growing within 6 months. Baldness occurs when the new strand fails to begin growing, or when the new hair strand is smaller and finer than the ones that grew from the follicle before that.

By the time men turn 60, more than two-thirds of them are either bald or have some hair loss.

Researchers don't completely understand the balding process. But they do know that the male hormone testosterone plays an important role. Heredity also determines whether a man will lose some or all of his hair, and when. The medical term for male pattern baldness is androgenetic alopecia.

The process is gradual, with the hairline moving back slowly. The hairline moves back into an M shape, and the crown begins to thin. Eventually, only hair around the sides of the head is left. Women also may have hair loss as they age, but the pattern is an overall thinning of the hair. The hairline does not recede.

A serious illness or major surgery can result in hair loss. Hormonal problems such as an over- or underactive thyroid can lead to hair loss. Medicines that can cause hair loss include blood-thinners (anticoagulants), chemotherapy medicines, gout medicine, birth control pills, and antidepressants. Too much vitamin A can cause hair loss. Hair loss may also be a sign of diabetes or the autoimmune disease lupus. In people with another autoimmune disease called alopecia areata, the immune system attacks the hair follicles. This causes widespread hair loss on the head and body. See your healthcare provider if you lose hair in patches, if it breaks off, if your scalp is red, painful, or itchy, or if the hair loss is rapid.

The medicine minoxidil is a treatment for the scalp (topical) that works for some men. Other men may be helped by the oral medicine finasteride. Hair grafts can be done. This mean surgically moving hair from one part of the head to the balding area. But all of these treatments are expensive, and the hair grafts are painful. For most men, baldness is permanent. Men should beware of any baldness "cures" marketed over the Internet or elsewhere. The FDA has approved the only medicines available for hair loss (minoxidil and finasteride). All other so-called remedies or treatments for baldness should be suspect. Taking advertised "hair growth" supplements to regrow your hair may seem like an easy solution, but getting too much of certain nutrients can make hair loss worse. All men who are bald or balding should wear a hat when outdoors to protect the scalp from UV exposure and possible skin cancer.