Sudden Hair Loss Telogen Effluvium
Telogen effluvium (TE) is a condition characterized by increased daily hair shedding. Normally, up to 100 telogen (club) hairs are shed daily. This is due to the fact that up to 10% of a person’s 100,000 scalp follicles are in telogen (the resting phase) at any given time (10% of 100,000 hair follicles is 10,000 hair follicles; with telogen lasting an average of 100 days this leads to an average shedding of 100 hairs/day). Most people actually shed 60 to 80 hairs a day because 6 to 8 % of their follicles are in telogen. TE is a perturbation of the hair cycle causing shedding of at least 120 hairs a day.
TE is caused by a sudden shift of growing anagen hairs into the catagen and subsequent telogen phases, culminating in shedding of these hairs. The shedding usually begins 2 to 5 months after the trigger because the average duration of catagen is 1 month and telogen usually lasts 3 months. Possible triggering events include severe medical illness, high fever, surgery, accidents, medications, crash diets, delivering a baby, discontinuation of oral contraceptive pills, or psychological trauma. Thyroid and iron deficiency can also lead to TE.