The horizontal section of a scalp specimen offers an advantage over a vertical area by providing quantitative information. The reference data for hair counts in Asians, including Thais, are inconclusive. We aimed to determine the expected values of hair counts in scalp biopsy specimens in the Thai population. A 4‐mm punch biopsy was performed at the scalp’s occipital area from subjects presenting clinically normal hair and scalp appearance. The researchers sectioned all specimens horizontally and observed to assess the number of follicular units and hair follicles, type of hairs, and the hair cycle phase. They compared the results further between sexes and with the pre‐existing data from previous studies.

The researchers have collected ninety specimens from 90 subjects. The mean number of total hairs, terminal hairs, vellus hairs, and follicular units per 4‐mm punch scalp skin were 20.5, 18.2, 2, and 9.1, respectively. The terminal’s mean ratio to vellus hair was 8.9:1 and of anagen to telogen hair was 91.9 : 7.9. No gender differences were in any of the parameters and no correlations with changing age. Compared to other Asian populations, Thais and Taiwanese showed intermediate values between Iranians and Koreans; compared to other ethnic groups, hair density in Asians showed lower than Caucasians and Hispanics but was comparable to Africans. This study established reference values of scalp horizontal sections in the Thai population; this will help clinicians and researchers evaluate hair disorders.

Ref: https://onlinelibrary.wiley.com/doi/10.1111/ijd.14989