Dealing with hair loss can be a traumatic experience for anyone. Taking the time to understand the main cause of the hair loss is key when trying to identify and treat the condition. Looking into the history of the prospective patient is a good starting point during hair loss evaluation. For example, if hair loss began in childhood there may be hereditary or genetic influences that should be explored.
Next it is good to understand focal versus diffuse hair loss patterns, which indicate different disease processes. For example, a focal area of loss could point toward alopecia areata, a localized tinea capitis, or trichotillomania. Diffuse loss may point toward a telogen effluvium, anagen effluvium or androgenetic alopecia.
It is important to discern whether the person is shedding hair or simply displaying thinning of hair. For example,alopecia areata and telogen effluvium are characterized by active hair shedding, whereas androgenetic alopecia is a condition of progressive hair thinning. If the hair is shedding though, then looking for a positive history of telogen effluvium would include identifying a recent fever, recent anesthesia, pregnancy, crash diet, etc. For a female, if the hair is simply thinning, more questions should be asked regarding iron deficiency, thyroid abnormalities, or irregular menses.
If the hair is in fact shedding, an appropriate question would be whether the hair is coming out by the roots or instead is showing signs of abnormal breakage. Telogen effluvium or androgenetic alopecia usually involves coming out of by the roots. Hair breakage, on the other hand, could simply occur due to harsh chemical treatments/hair-care products, but may also be some kind of anagen effluvium, such as following chemotherapy for cancer. Abnormal hair breakage can also be caused by infections like tinea capitis or other conditions that cause structural hair shaft defects.
Clinical Hair Loss Evaluation
Upon collecting a careful history from the patient, a physical examination of the scalp and hair should be completed. In the case of non-scarring alopecias, the area of hair loss will still maintain visible follicular units, but with scalp scarring the area of hair loss will have no follicular units, which may lead to a similar appearance of scarring, scaling, and associated redness. Examining the pattern and distribution of the hair loss may lead to the cause. Determining caliber, fragility, length, and shape can be accomplished by evaluating the hair shaft.
Before performing a pull test, the patient should refrain from showering for a day to gain more accurate results. A pull test is performed by grasping approximately 60 hairs between the thumb, forefinger, and middle finger then gently tugging the hairs. An abnormal pull test is indicated when greater than 10% of hairs are released when tugged. The pull test will help remove the telogen hairs, but should not remove the normal anagen hairs. Having an excessive number of telogen hairs may be indicating telogen effluvium. Abnormal anagen hairs may also be pulled out, which may indicate a loose anagen syndrome or dystrophic and fragile anagen hairs. Usually, these fragile anagen hair shafts will break somewhere along the shaft without displaying any roots. The pulled hairs can then be evaluated on a glass slide under a microscope. To distinguish from anagen hairs, look for the classic club-shaped and semi-transparent root that telogen hairs display.
Pluck Test- (Trichogram)
A trichogram or pluck test requires the use of a 60 to 80 hairs are firmly grasped and forcefully plucked, twisted, and lifted out of the scalp using a hemostat with a rubberized end. Hairs shafts are then cut 1 cm above the root so that the roots may be evaluated side by side on a slide under a microscope. During this process, anagen hairs are distinguished from telogen hairs to establish anagen/telogen ratios. Dystrophic or damaged anagen hairs should not be considered pathologic, but a result of their forceful removal because the forceful tug of the anagen hairs most likely will show artefactual changes. Due to the inaccuracy of results (and the discomfort involved), the trichogram is rarely used today.
Performing daily scalp counts can be helpful when collecting information regarding the cause of hair loss. Approximately 100 to 150 hairs per day is the normal amount for physiologic hair loss. To perform an accurate count, the shed hairs should be collected from brushes, sinks, and the shower then placed daily into separate plastic bags. It is important to note days in which showering occurs because increased shedding is expected with showering. A daily scalp count should span a 7-day period. If someone is losing fewer than 100 hairs per day they may be considered to have no active shedding. The individual can determine progress or worsening of hair shedding by repeating the process at intervals.
Performing a scalp biopsy can be very informative and simply a biopsy of 4mm wide and 4 mm deep is made in an area of active hair loss. In the past, the biopsy was sectioned vertically to evaluate the longitudinal nature of each hair shaft. Today though it is believed that a transverse or horizontal section can be more informative when identifying how the hair shafts relate to one another, which assists with better understanding the anagen to telogen ratios. The biopsy is sectioned horizontally to evaluate the upper level, mid-level, and deeper levels. The upper level consists of the papillary dermis, the mid-level is located at the reticular dermis, and the deeper levels are within the subcutaneous fat. Usually, all telogen and anagen hairs as well as terminal and vellus hairs are located in the upper levels. The mid-levels contain only terminal hairs consisting of the anagen and telogen hairs. The deep levels on the other hand only hold canagen and terminal hairs. Hence, horizontal sectioning allows for anagen/telogen ratios and terminal/vellus hair ratios to be calculated. Other laboratory work can be done to assist with the scalp biopsy. Some of this associated lab work may consist of serum ferritin to rule out iron deficiency anemia as the cause of hair loss. Thyroid functioning tests may also be required at times to provide a thorough work up, especially with instances involving female hair loss.
Missouri Hair Institute
556 Rush Creek Pkwy, Suite B
Liberty, MO 64068