Telogen effluvium is a common cause of transient hair loss caused by the excessive shedding of resting or telogen hair following a physiological shock. The growth of new hair continues. Because of the form of the root, telogen hair is also known as club hair.
It should be differentiated from anagen effluvium, in which hair loss is caused by medications, toxins, or inflammation interfering with active or anagen hair growth (eg, alopecia areata). The tip of anagen hair is pointed or tapered.
What is telogen effluvium and what causes it?
About 85 percent of hair follicles in a healthy person’s scalp are actively producing hair (anagen hair), while the remaining 15% are resting hair (telogen hair). A few hairs may be in catagen as well. A hair follicle develops anagen hair for about four years and then rests for about four months. A new anagen hair emerges from behind the resting telogen hair, pushing it out.
As a consequence of the natural scalp hair cycle, it is typical to shed up to 100 hairs every day on one’s comb, brush, in the basin, or on the pillow.
If the body is shocked, up to 70% of anagen hairs can be converted to telogen, reversing the normal ratio. The following are examples of common triggers:
- Postpartum hair loss is a common side effect of childbirth. After a few months, this may resolve or progress to female pattern alopecia.
- Hair loss in infants is caused by a physiological process.
- Illness, whether acute or chronic, especially if there is a temperature
- Surgical procedure
- Stress on the mind
- Weight loss, a strange diet, or a nutritional deficit (e.g., iron deficiency) are all possibilities.
- a number of medicines
- Endocrine problems (eg, hypothyroidism, hyperthyroidism)
- Taking the contraceptive pill off the market
What do the symptoms of acute telogen effluvium look like?
Telogen effluvium is a non-scarring kind of widespread hair loss that affects up to 50% of the scalp hair and has no clinical or histological signs of inflammation.
Initially, the resting scalp club hairs are securely connected to the hair follicles. The resting club hairs are pushed out by new hairs coming up through the scalp, resulting in increased hair fall 2 to 4 months after the triggering event.
Hair fall is, ironically, a sign of hair regeneration with this kind of hair loss.
A fine fringe of new hair is typically seen around the forehead hairline when new hair emerges from the scalp and pushes out the dead hair.
Club hairs fall profusely at first, and a general thinning of the scalp hair may appear, but after several months, a peak is achieved, and hair fall begins to diminish, gradually tapering back to normal in most cases over 6–9 months.
The scalp thickens back up to normal when hair fall slows, but in some situations, recovery may be partial.
How is telogen effluvium diagnosed?
Clinical characteristics are generally used to diagnose telogen effluvium.
Hair thinning affects the entire scalp as well as the hair on other parts of the body.
The examination reveals widespread thinning with short hairs of normal thickness and no localised regions of complete alopecia.
A mild hair pull reveals a greater number of hairs, the majority of which are telogen and have a characteristic epithelial sac.
A trichogram can assist confirm the diagnosis; a trichogram with more than 25% telogen hairs strongly supports telogen effluvium.
Club hair is visible under a light microscope.
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