Causes of Hair Loss
Everyone loses at least 100 scalp hairs a day. Even people with full, beautiful heads on hair often find lost follicles clogging the shower drain after a day or two. Yes, there are even celebrity hair transplants. The point is, all hair falls out—it is in its natural genetic program to do so.
The normal life cycle of a hair is hair growth (anagen), is maintained (catagen), and eventually falls out (telogen). Baldness does not occur unless this normal life cycle is disrupted for some reason. In certain types of alopecia, hair follicles begin to spend more time in telogen than in anagen or catagen. If this balance shifts too much to telogen, hair that is lost is not replenished and apparent balding occurs. This type of hair loss is seen in androgenetic alopecia or pattern baldness.
The most common type of permanent hair loss is androgenetic alopecia, or pattern baldness. In men it causes a receding hair line, loss of hair on the vertex of the head, and baldness in predictable areas of the scalp over time.
In both men and women, pattern baldness is genetically predetermined. While the gene most often responsible for pattern baldness is found on the X chromosome. This means that the genetic predisposition to pattern baldness can be inherited from mother, father, or both parents. While some of the genes associated with hair loss are dominant (they will cause a physical change regardless of the other genes present), androgenetic alopecia only occurs in those with certain genes and in the presence of certain hormones. Fortunately, there are effective hair loss treatments for pattern baldness.
It has been known for centuries that certain types of hair loss are linked to hormones. If boys are castrated prior to puberty, they do not develop androgenetic alopecia regardless of their genes. Likewise, men with androgenetic alopecia have increased levels of certain hormones in their scalp. One notorious hair-killing hormone is dihydrotestosterone or DHT. In fact, many hair loss treatments are aimed at lowering or blocking the effects of DHT in the scalp.
The stress that leads to human hair loss is not necessarily psychological stress but rather a physiological stress to the body (although these two conditions can be related). When the body is subjected to some sort of physiological stress it can place hair follicles in a state of nearly immediate and simultaneous telogen—a condition known as telogen effluvium. Stresses that can cause telogen effluvium include:
- Acute illness (infection, major surgery, trauma)
- Chronic illness (cancer, end stage kidney and/or liver disease, lupus)
- Hormonal fluctuations (pregnancy, endocrinological diseases)
- Nutritional deficiencies or aberrations (anorexia, protein malnourishment, vitamin deficiencies, heavy metal poisoning)
Telogen effluvium occurs in both genders at virtually any age. It is often thought to occur in women more frequently than men for two reasons. First, the stresses of pregnancy and childbirth can lead to telogen effluvium and second, women seek medical attention for this type of hair loss more frequently than men.
Read: Keep Your Hair OnRead: Hair Growth Cycle
There are many causes of hair loss ranging from genetic to intrinsic to external factors. The proper hair loss treatment depends on identifying the cause. Often it is necessary to consult with a physician that is experienced with the diagnosis and treatment of all types of alopecia, such as a dermatologist, to determine the cause of hair loss.
Genetic causes of alopecia are best treated by focusing on the hormonal component of the disease (finasteride, minoxidil) or through follicular unit transplantation. Hair loss caused by physiological stresses requires medical attention since the best treatment for these conditions is to remove or treat the disease state. Once the stressor is removed, the hair should return to anagen and grow again