Telogen effluvium
Telogen effluvium is the name for hair loss due to shedding of excessive numbers of resting or telogen hair. New hair continues to grow. Telogen effluvium can be acute (single episode i.e. temporary shedding) or chronic (persistent shedding over a long period of time). Although the loss of excessive amounts of hair during telogen effluvium may reduce the overall bulk of the hair, it does not result in baldness.
It should be distinguished from anagen effluvium, in which hair shedding is due to interruption of active or anagen hair growth by drugs (e.g. chemotherapy), toxins or inflammation (e.g. alopecia areata), which can cause baldness.
Telogen effluvium
Normal hair loss
In a normal healthy person's scalp about 85% of the hair follicles are actively growing hair (anagen hair) and 15% are resting hair (telogen hair). Anagen hair has a pointed or tapered tip. Telogen hair has a bulb or club-shaped tip.
A hair follicle usually grows anagen hair for 4 years or so, then rests for about 4 months. A new anagen hair begins to grow under the resting telogen hair and pushes it out. Thus, it is normal to lose up to about 100 hairs a day on one's comb, brush, in the basin or on the pillow, as a result of the normal scalp hair cycle. Most of these are bulb hairs with a club-shaped tip.
Acute telogen effluvium
Acute telogen effluvium usually follows some shock to the system, when as many as 70% of the anagen hairs can be precipitated into telogen. Typical precipitants include:
Illness, especially if there is fever
Surgical operation
Accident
Childbirth
Nervous shock
Weight loss or unusual diet
Certain medications
Discontinuing the contraceptive pill
Overseas travel resulting in jetlag
Excessive sun exposure
The resting hairs remain firmly attached to the hair follicles at first. About 2 months after the shock, new hairs coming up through the scalp push out the telgoen hairs and increased hair fall is noticed.
Thus, paradoxically, with this type of hair loss, hair fall is a sign of hair regrowth. As the new hair first comes up through the scalp and pushes out the dead hair a fine fringe of new hair is often evident along the forehead hairline. At first the fall of club hairs is profuse and a general thinning of the scalp hair may become evident, but after several months a peak is reached and hair fall begins to lessen, gradually tapering back to normal over 6-9 months. As the hair fall tapers off the scalp thickens back up to normal, but recovery may be incomplete in some cases.
