The texture of hair is a result of both the thickness of the individual strands and the density of hairs on the scalp.
Scalp hair grows at about 0.6 – 1.25cm per month, and will normally reduce in thickness and density with age. Hair is at its thickest in a person´s early 20´s and gradually reduces thereafter. The thickness of hair ranges from fine to coarse, and varies between different ethnic groups and people. Fine hair has a diameter of about 50µm (microns) and because of its narrow size is most susceptible to breakage.
Medium hair has a thickness of 60-90µm and is the most common. Coarse hair is relatively strong with a thickness of 100µm or more. Miniaturisation is the occurrence of hair loss, as the hair shaft begins to atrophy the hair diameter decreases, this can be due to androgenic alopecia in the recipient or donor are- as. In the donor this can result in reducing the donor capacity and even make the donor unsuitable for a hair transplant. Transplanting miniaturised hairs can result in a poor result; the trauma of the harvesting can cause these hairs to not grow and also have an impact of the surrounding hairs remaining in the donor.
It is normal to have a slight amount of miniaturised hair in the donor especially in later age, but if the miniaturisation exceeds 15% of the donor density then potentially a hair transplant is not advisable due to a traumatised donor area.