History
The symptom of both acute and chronic telogen effluvium is increased hair shedding. Patients usually only complain that their hair is falling out at an increased rate. Occasionally, they note that the remaining hair feels less dense. In both forms of telogen effluvium, hair is lost diffusely from the entire scalp. Complete alopecia is not seen.
Acute telogen effluvium is defined as hair shedding lasting less than 6 months. Patients with acute telogen effluvium usually complain of relatively sudden onset of hair loss. Careful questioning usually reveals a metabolic or physiologic stress 1-6 months before the start of the hair shedding. Physiologic stresses that can induce telogen effluvium include febrile illness, major injury, change in diet, pregnancy and delivery, and starting a new medication. Immunizations also have been reported to cause acute hair shedding. Papulosquamous diseases of the scalp, such as psoriasis and seborrheic dermatitis, can produce telogen effluvium.
Chronic telogen effluvium is hair shedding lasting longer than 6 months. The onset is often insidious, and it can be difficult to identify an inciting event. Because of the duration of the hair shedding, patients are more likely to complain of decreased scalp hair density, or they may note that their hair appears thin and lifeless. Visual analog scales can help patients to assess the severity of hair shedding. [25]
Physical Examination
The physical examination is the same in both acute and chronic telogen effluvium. Physical findings are sparse. Usually, the physician does not appreciate a decrease in hair density. However, if the patient's hair has been falling out for several months, the hair may appear thin when compared with old photographs.
Depending on the duration of hair loss, close examination of the scalp may reveal a higher than expected number of short new hairs growing. Because hair grows at a nearly constant rate of approximately 1 cm per month, the duration of the hair shedding can be estimated by measuring the length of the short hairs. Trichoscopy can be helpful in visualizing the hairs. [26]
In active telogen effluvium, the gentle hair-pull test yields at least two hairs with each pull. [27] If the patient's active shedding has ceased, the hair pull will be normal. Forced extraction of 10-20 hairs will yield a large percentage of telogen hairs. If greater than 25% of extracted hairs are in telogen, the diagnosis of telogen effluvium is confirmed.
There is one caveat to reliance on strict physical findings or numerical criteria in the diagnosis of telogen effluvium. Each patient's scalp hair has an individual characteristic growth cycle. There are patients who have a very long anagen phase and a small proportion of hair in telogen at any given time. These patients may experience an episode of telogen effluvium but have completely normal physical findings. History alone must guide the physician to the correct diagnosis in these cases.
There should be no areas of total alopecia in a patient with telogen effluvium. Scarring is not present. There also should be no sign of an inflammatory scalp dermatitis. Usually, there are no complaints of body hair loss.
-
Telogen effluvium secondary to hypothyroidism.
