There are many causes of hair loss. Some are benign and come with heredity and age while others can signal underlying medical problems. Anyone with unexpected or irregular hair loss should consult with a physician for evaluation.
Significant trauma or illness can cause telogen effluvium. Basically hair falls out and is pushed into the resting part of the hair cycle. Usually within about 6 months of the trauma, the hair will start to grow again.
Chronic medical diseases
Chronic conditions such as diabetes and low thyroid hormone levels can cause balding. Usually once the underlying medical condition is controlled, the hair will regrow.
Wearing hair in a tight braid can cause scarring of the hair follicles and cause hair loss over time. If scarring has occurred, this can be permanent.
Certain psychological conditions cause patients to irrationally pull out their hair. Unfortunately the alopecia can be permanent when scarring occurs in the areas which are pulled out. Patients require counseling and sometimes medications to treat this troublesome problem.
Many different types of medications can cause balding or hair thinning. Unfortunately some vitamins which are taken to grow hair can cause loss when the vitamins are taken in large doses. In most cases, when the offending medication is discontinued, the hair will regrow.
A localized form of hair loss which can progress to a whole body alopecia, alopecia areata is thought to be an autoimmune disorder. In this condition, it is thought that the body somehow determines that the hair follicle is a foreign object and fights it off, killing the follicle. Though treatments in some instances can cause hair regrowth, there is no universally accepted treatment algorithm and hair transplant surgery may be necessary.
Commonly termed male pattern baldness is a condition which can also affect females though with a different result. Balding is due to the effect of androgens, actually break down products of testosterone, on certain hair follicles. In men, this type of hair loss only takes place on the top of the head and the crown of the head. Certain areas of the scalp will not be effected nor will the rest of the body. The cause is multifactorial. Genetically, the hair loss can come from your mother's side of the family or your father's side. It may skip generations and the degree of hair loss may vary between effected individuals in the same family. Type of hair this loss is salves are particularly suited to being Treated with hair transplants .