Telogen effluvium

Telogen effluvium is characterized by sudden, diffuse hair loss caused by an interruption in the normal hair growth cycle.

Causes
This interruption is often the result of trauma, such as chemotherapy, childbirth, puberty, major surgery, severe stress, and severe chronic illness. This trauma causes large numbers of hair follicles to enter a stage of telogen, or rest, simultaneously. After roughly 3 months of the telogen cycle the follicles will enter the anagen cycle, a stage of growth. The old hair will be forced out of the follicle by a new hair that is formed beneath it. This will cause a period of diffuse hair shedding. This condition is usually self correcting and can affect people of all ages.

Classification
There is also another form of telogen effluvium referred to as 'chronic'. This is essentially the same except it is on-going.

Presentation in pregnancy
A typical example of telogen effluvium is seen after pregnancy. In this condition women lose a significant amount of hair a few months after delivery when the protective effect of estrogen is removed. This shedding usually stops spontaneously and these patients will re-grow hair after 3 months.