Hair density, hair diameter and the prevalence of female pattern hair loss

Abstract

Hair density in women is distributed as a normal variable, indicating that it is determined as a multifactorial trait. Women with female pattern hair loss have a hair density which falls below the mean but lies within the spectrum of the normal distribution, although other factors, including hair diameter, may affect the subjective impression of hair loss. The hair diameter data suggest that low hair density is not due to progressive diminution in hair follicle size and that follicular miniaturization may occur within the space of a single hair cycle.

Controlled clinical trial for evaluation of hair growth with low dose cyclical nutrition therapy in men and women without the use of finasteride

“…Pattern hair loss can occur with normal androgen levels [12,13] , pattern hair loss can occur before puberty [13][14][15] , it has been reported in hypogonadism [16] and also in a case of complete androgen insensitivity syndrome [17] . Instead of insisting on anti-androgens in management of hair loss patients, we should focus on strengthening the hair follicle and promoting better hair growth to ensure more hair on the head.…”

Hair: A Review of Prominent Scalp Hair Changes throughout a Females’ Life

“…Birch et al, [8] measured hair shaft diameters in hair samples taken from 294 women. Mean hair diameter, increased from age 22 years to a peak in early-to mid-thirties and then gradually declined with advancing age.…”

“…This occurs to a greater degree over the trunk and limbs than over the head so that the reduction in follicle density is less marked on the head than elsewhere. There is also racial variation in scalp hair density: average scalp hair density in white people varies between 250 and 320 hairs/cm 2 [8], in Africans it's about 187/cm 2 [9] and African Americans 171/cm 2 which is lower than in white people, and it is even lower in Koreans as it is 128/cm 2 [10]. It has been reported that in normal females, the top of the head shows the highest mean hair density, followed by front, back, and sides in decreasing order [11].…”

“…Birch et al, [8] measured hair density on the mid ⁄frontal scalp in an unselected sample of women. At all ages there was a wide, normally distributed scatter in hair density.…”

Selected variants of the steroid‐5‐alpha‐reductase isoforms SRD5A1 and SRD5A2 and the sex steroid hormone receptors ESR1, ESR2 and PGR: No association with female pattern hair loss identified

“…The disorder is termed male pattern baldness in men, and female pattern hair loss (FPHL) in women. FPHL affects around 12% of women by the age of 30 years, and 30-40% of women by the age of 70 years (1)(2)(3). Women with FPHL typically present with diffuse and progressive thinning of the hair at the crown.…”