Method:
(1) A small group of hairs (approximately 50) is identified on the scalp.
(2) A hemostat with thin tubing placed over the jaws is clamped onto these hairs.
(3) The hairs are then rapidly yanked from the scalp (yow!).
(4) The hairs are placed on a glass slide so the deepest portions can be examined under a microscope.
Types of terminal hairs counted:
(1) anagen hairs
(2) telogen hairs (with cornified club at proximal end)
(3) catagen hairs (usually uncommon)
(4) dysplastic hairs
Most hairs will be either anagen or telogen hairs.
The forcible removal of hairs can result in a variety of artifacts in anagen hairs. Distorted hairs that are counted as anagen include:
(1) hairs with a snapped off shaft (straight cut surface, as if cut with scissors)
(2) hairs with a pigmented, bent root and ruffling of the cuticle over the proximal shaft (findings caused by the forcible removal of the root sheath)
(3) hairs with a remnant of an outer or inner root sheath
total hair count =
= (number of anagen hairs) + (number of telogen hairs) + (number of catagen hairs) + (number of dysplastic hairs)
telogen count =
= (number of telogen hairs) / (total number of hairs) * 100%
Interpretation:
• Stanimirovic et al found 13-15% telogen hairs in their normal controls.
• Patients with alopecia often will have an increase in the telogen count.
• Dysplastic hairs are uncommon in normal hair but may be present in significant numbers in psoriasis and other skin disorders.
Limitations:
• Too few hairs examined will result in statistical errors.
• The method is highly dependent on the experience of the examiner.
