A: You’re referring to Hair DX (hairdx.com), which costs about $150 and came to market in January of 2008 as the first test for androgenetic alopecia, aka male pattern baldness.

The test screens for variations in the androgen receptor gene on the X chromosome, the gene that is associated with male pattern hair loss. The purpose of the test is to identify persons at increased risk of developing hair loss before it is clinically apparent – so that medical intervention can be started early, when it is most effective.

It is important to realize that, at this point, there is just an association with this gene and hair loss; the cause and effect has not been proven and the association is not anywhere near 100%. A danger is that patients may overreact to the relatively incomplete information that the test provides. It is best to have the test performed under a doctor’s supervision, so that it can be put in the context of other information that the physician gleans through a careful history, physical and a densitometry hair evaluation. As of this posting, genetic testing for hair loss is not permitted in New York State.

A: Diffuse hair loss, more common in women, can be the result of a number of underlying medical conditions and therefore it usually requires an extended medical evaluation. We charge $350 for this evaluation.

If you are a male or female with obvious diffuse thinning from androgenetic alopecia (common baldness), or if you have patterned hair loss where the diagnosis is straightforward, the fee is $125.

A: As you suggest, it would be reasonable to assume that since DHT stimulates beard growth, blocking DHT (with finasteride) would tend to inhibit its growth. In practice, this does not seem to be the case, i.e. we don’t find that Propecia has any affect on facial hair. The reason is not clear.

It is interesting to note that testosterone stimulates growth of axillary and pubic hair, but not scalp hair. Scalp hair growth is not androgen dependent, only scalp hair loss is.

DHT stimulates terminal hair growth of the beard, trunk and limbs, external ears and nostrils. Of course, it also is responsible for the bitemporal reshaping of hairline as one passes into adulthood and causes male patterned baldness (androgenetic alopecia).

A: Miniaturization is the decrease in hair shaft length and diameter that results from the action of DHT on healthy, full thickness terminal hairs. The hairs eventually become so small that they resemble the fine, vellus hair normally present in small numbers on the scalp and body. Miniaturized hairs have little cosmetic value. Eventually miniaturized hairs will totally disappear. Twenty percent miniaturization refers to the observation, under densitometry, that 20% of the hairs in an area show some degree of decreased diameter.

In the evaluation of candidates for hair transplantation, we use the 20% as a rough guide to include all hairs that are not full thickness terminal hairs. Of course we are most interested in the presence of intermediate diameter hairs – i.e. those whose diameters are somewhere between terminal and vellus and are clearly the result of DHT. I don’t know if one can tell the difference on densitometry between vellus hairs, fully miniaturized hairs and senile alopecia. The partially miniaturized population is most revealing.

Miniaturization in the recipient scalp (i.e. the balding areas on the front top and crown that we perform hair transplants into) is present in everyone with androgenetic hair loss. Miniaturization in the donor area, however, is less common (in men). It means that the donor area is not stable and will not be permanent. Men with more than 20% of the hair in the donor area showing miniaturization are generally not good candidates for hair transplant surgery.

A: In androgenetic hair loss one rarely sees hair falling out in mass, but rather the thinning is due to the hair decreasing in diameter and length (a process called “miniaturization”).