This type of “hair test" is done by a hair transplant surgeon or dermatologist to find out the rate of telogen hiar. It’s a simple procedure. The doctor pulls hair to find out the number of hair follicles in the resting phase. The way the test works is that the doctor grasps a couple of hair shafts between the pointing finger and thumb, then pulls them ever so softly. There are two classifications of hairs: Anagen, which are growing hairs that ought to remain in place; and telogen: hairs that should pull out rather easily.
By keeping track of the number of pulled hairs, a person can approximately calculate, in the telogen state, the hair follicle percentage. For example, if a person pulls on 10 hairs and then 2 come out, then the telogen hair follicles frequency is 20%. If extracted hair follicles percentage is up to 25%, that is still considered OK, but if it’s over 35%, it is not normal and shows that there’s a disproportionate amount of hair in the resting phase. This condition is often seen in Telogen Effluvium (TE).
Even though this hair-pulling test seems simple, a person may come to the wrong conclusions if they do not carry out the test properly and he or she does not have a full comprehension of the test’s limitations. The biggest concern is that the test results may be affected by what the patient did with her hair in the preceding hours. When the patient washes her hair, it will cause many of the telogen hairs to fall out.
There are several factors which can increase the accuracy of the hair pull test. The hair pull test can be ratcheted up to another level by conducting the "unit area trichogram". This type of test requires that a couple hair follicle samples are grabbed from the scalp utilizing rubber-covered forceps; both telogen and anagen hairs are yanked. These hairs are to be placed on a glass slide and inspected using a microscope. After that, the dermatologist is to count up the telogen hairs and the anagen hairs as well. The test can help the doctor in differentiating a variety of hair loss conditions.