Understanding hair diagnostics: the hair pull test, hair tug test, and hair mount test explained

The hair pull test, hair tug test, and hair mount test are key diagnostic procedures that dermatologists use during consultations with patients experiencing hair disorders. These simple, non-invasive tests can reveal important information about the health, growth, and structural integrity of the hair, helping clinicians diagnose conditions such as alopecia areata, telogen effluvium, anagen effluvium, androgenetic alopecia, loose anagen syndrome, and various hair shaft disorders.

Hair pull test: The hair pull test, also known as the hair traction test, is a standard diagnostic procedure for determining active hair loss. It involves a dermatologist gently tugging on 50-60 hair fibers from different areas of the scalp. The severity of hair loss is gauged by the number of hairs that come out when pulled. A positive hair pull test, which is when more than five or six strands fall out during the test, indicates an active hair loss process. The hair pull test is usually performed when acute or chronic telogen effluvium hair loss is suspected (telogen effluvium is a diffuse hair loss that more commonly affects women, but can also affect some men).

The hair pull test can also be performed if pattern hair loss is suspected, but the pattern is not clear from a visual examination. It’s worth noting that there’s no scientific test to definitively determine hair follicle miniaturization, as seen with pattern hair loss, but the hair pull test can be indicative of it if more than three strands fall out during the procedure.

Please note. If you suspect your dermatologist will physically examine your hair, you should not wash your hair the morning of a consultation! When you wash your hair you remove many of the loose hairs. This means that when a dermatologist does a hair pull test he/she may obtain a false negative result. Not washing your hair will allow a more accurate hair pull test to be made.

Hair tug test: The hair tug test, is used to detect hair shaft fragility. This test is performed by holding a group of 50-60 hairs with the thumb and forefinger of one hand and gently pulling away the distal ends with the other hand. Any hair breakage is considered abnormal and indicative of hair fragility. This broken hair can then be used in a hair mount test.

Hair mount test: The hair mount test involves microscopic examination of the hair bulbs and hair shafts. It’s performed by placing epilated (pulled out) hair roots on a glass slide, adding a mounting medium, arranging the roots side by side, and then covering the mount with a coverslip. Light microscopy is then used to examine the hair mount. This test can reveal structural abnormalities in the hair shaft and provide insight into the stage of the hair cycle based on the appearance of the hair root.

For instance, growing anagen hair has a darkly pigmented bulb with a preserved inner root sheath, while telogen hair, that come from follicles in an inactive resting stage of the hair growth cycle, lacks this sheath and typically features a lightly pigmented to nonpigmented bulb with a distinctive club shape. Microscopic examination can help diagnose various hair shaft disorders, such as monilethrix, trichorrhexis invaginata, trichorrhexis nodosa, pili annulati, pili torti and several others.

While these tests provide valuable information about hair health, it’s crucial to remember that they should be performed by a trained professional. A dermatologist or trichologist can correctly interpret the results and offer appropriate treatment options based on the findings. Furthermore, although newer techniques like trichoscopy have made hair mounts less necessary, they remain a valuable tool in the dermatologist’s arsenal, especially when looking for specific hair shaft abnormalities.

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