Q: Why should a doctor measure miniaturization in the donor area before recommending a hair transplant? — E.B., Key West, F.L.
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.