- anagen, the growing phase, characterized by active hair cell division. Toward the end of the anagen phase, the amount of hair pigment decreases, then,
- the hair enters the catagen phase, a transitional phase in which hair cell division slows down. And
- telogen phase: the resting phase
The hairs remain in this resting state until the hair follicle re-enters the anagen phase. At this point, the club hairs are forced out by growing hairs underneath them, and the cycle begins all over again. The cycle is not synchronous throughout the scalp. The length of each phase of the cycle, as well as the length of the entire cycle, varies with the site and the age. So for example, in the scalp, the average length of the anagen phase is 1000 days; the catagen phase lasts only a few days; and the telogen phase lasts 100 days.
Of the 100,000 hairs on the average scalp, 10-15% is in the catagen or telogen phase at any time. Most hair follicles are in the anagen stage at any given time.
How to detect if there is physiologic (part of hair cucle) or pathologic (due to disease) hair loss?
DAILY HAIR COUNTS
This method can be useful to help estimate how much hair you are losing and make sure that this is not more than the physiologic hair loss. The normal rate of hair loss is up to 100 hairs per day. What you need to do is collect hairs shed in one day, count them and place them in plastic bags. All shed hairs, including in the shower or sink or on the brush, should be collected. Hair count should be done daily for a total of 7 days. It is expected to lose more hairs on shampoo days.
If you are losing more than 100 hairs per day, the hair should be examined microscopically to detect any disease process in the hair bulb or hair shaft. Appearance of the hair bulb can distinguish between:
- telogen effluvium , a scalp disorder where there is the thinning or shedding of hair resulting from the early entry of hair in the telogen phase (the resting phase of the hair follicle). Generally, recovery is spontaneous and occurs within 6 months
- anagen effluvium: occurs after any insult to the hair follicle that inhibits cell division, and
- active diffuse alopecia areata: the hair falls out in round patches. The hair can fall out on the scalp and elsewhere on the body.
STANDARDISED WASH TEST
In the wash test, you should not from shampoo your head for 5 days, and then you shampoo and rinse your hair in the basin while covering the entire thing with gauze or a thin cloth. The hairs caught in the water and the gauze are collected and sent for examination. Hairs must be counted and divided into ≤3cm and ≥5 cm in length.
60-S HAIR COUNT
The technique comprises of the following four steps:
1. Before shampooing, comb your hair for 60 seconds over a pillow or sheet of contrasting color to your hair, starting with the comb at the base of your scalp and moving the comb forward to the front of the scalp.
2. Repeat the procedure before three consecutive shampooings (e.g., if you shampoo every other day, then repeat the procedure every other day) and always use the same comb or brush.
3. Count the number of hairs in the comb or brush and on the pillow after each hair count and record.
4. Repeat the above procedure monthly and bring the results to your dermatologist.
About 20-60 hairs are grasped between the thumb, index and middle fingers from the base of the hairs near the scalp, firmly, but not forcefully, tugged away from the scalp. If > 10% hairs are pulled away from the scalp, this is a positive pull test result and implies active hair shedding. The patient must not shampoo for at least a day prior to the pull test.
Of course, the results of such tests need to be interpreted by a dermatologist. And you need to remember they are not 100% accurate, so a dermatologist’s opinion/intervention will be ultimately required for proper diagnosis and treatment.