Q: Dr. Bernstein, can you please comment on leg and body hair transplants? — J.R., Ridgewood, NJ

A: I’ve tried the technique in the past but have been dissatisfied with the results. Scalp hair, unlike the rest of the body, has multiple hairs rising out of each follicle. With leg and body hair, you have only one hair per follicle, not follicular units of multiple hairs. Leg hair is also very fine. It might thicken up a little bit after it is transplanted, but not enough to be clinically useful. In men you want full thickness hair, so fine hair can make it look like it is miniaturizing, as it does when you’re losing it.

Body hair has been successful in softening hairlines, but most people have enough scalp hair to due this, since it often requires very little if properly placed. Another issue is that because leg hair emerges from the skin on a very acute angle, more wounding of the skin occurs as each hair is individually extracted and this leaves marks.

Body hair, from the chest or back, does hold better potential for success than leg hair, particularly if it is plentiful, but it still is extracted one hair at a time and can leave significant scarring when done in large numbers.

Read about the traditional donor area on the back of the scalp

Q: I was told that I have low hair density in the donor area. Would multiple procedures be possible to improve the result? — J.G., Hoboken, NJ

A: Yes, but subsequent procedures would be smaller and there is a point of diminishing returns where additional procedures would yield so little hair that they would not be practical. There is a finite donor supply and once this is tapped, no more hair transplants are possible, regardless when one uses FUT or FUE.

Q: Why should a doctor measure miniaturization in the donor area before recommending a hair transplant?

A: Normally, the donor area contains hairs of very uniform diameter (called terminal hairs). In androgenetic hair loss, the action of DHT causes some of these terminal hairs to decrease in diameter and in length until they eventually disappear (a process referred to as “miniaturization”). These changes are seen initially as thinning and eventually lead to complete baldness in the involved areas.

These changes affect the areas that normally bald in genetic hair loss, namely the front and top of the scalp and the crown. However, miniaturization can also affect the donor or permanent regions of the scalp (where the hair is taken from during a hair transplant). If the donor area shows thinning, particularly when a person is young, then a hair transplant will not be successful because the transplanted hair would continue to thin in the new area and eventually disappear. It is important to realize that just because hair is transplanted to another area, that doesn’t make it permanent – it must have been permanent in the area of the scalp it initially came from.

Unfortunately, in its early stages, miniaturization cannot be seen with the naked eye. To detect early miniaturization a doctor must use a densitometer, or an equivalent instrument, that magnifies the surface of the scalp at least 20-30 times. This enables the doctor to see early changes in the diameter of the hairs that are characteristic of miniaturization. If hairs of varying diameter are noted (besides the very fine vellous hairs that normally occur in the scalp), it means that the hair is being affected by DHT and the donor area is not truly permanent.

In this situation, a person should not be scheduled for hair transplantation. If the densitometry reading is not clear, i.e. the changes are subtle and the doctor is not sure, then the decision to have surgery should be postponed. By waiting a few years, it will be easier to tell if the donor area is stable. Having surgery when the donor area is miniaturizing can be a major problem for a patient, since not only will the transplanted hair eventually disappear, but the scar(s) in the donor may eventually become visible. This problem will occur with both follicular unit transplantation (FUT) and follicular unit extraction (FUE).