The Hair Cycle And Its Regulation
October 1988
in “
Clinics in Dermatology
”
hair cycle anagen catagen telogen hormones estrogens thyroid hormones androgens hair shedding follicles telogen phase scalp hair diameter diffuse alopecia endocrine abnormalities malnutrition protein deprivation marasmus hair root diameters hair growth phases hair loss hair thinning hair follicles hair diameter hair shedding protein deficiency
TLDR Hormones, nutrition, and seasonal changes regulate hair growth cycles, with androgens extending growth phases and factors like aging and malnutrition affecting hair loss and thinning.
In 1988, F. John G. Ebling provided an overview of the hair cycle, which includes anagen, catagen, and telogen phases, and how it is regulated by factors such as hormones, nutrition, and seasonal changes. The paper highlighted the influence of estrogens, thyroid hormones, and androgens on the duration of these phases, particularly noting that androgens can prolong the anagen phase in androgen-dependent hair. It was observed that hair shedding may peak in autumn and that the percentage of follicles in the telogen phase increases with age. The study also discussed the evolutionary role of hair in mammals and its clinical significance. The document included data on scalp hair diameter distribution in normal women, those with diffuse alopecia with and without endocrine abnormalities, and the impact of severe malnutrition and protein deprivation on hair growth, citing that less than 1% of hair roots were in the anagen phase during marasmus and that hair root diameters decreased with protein deprivation but were reversible with protein reintroduction.
