Types of hair loss
Types of hair loss
The word “alopecia” is the medical term for hair loss. Alopecia does not refer to one specific hair loss disease – any form of hair loss is an alopecia. The word alopecia is Latin, but can be traced to the Greek “alopekia,” which itself comes from alopek, meaning “fox.” Literally translated, the word alopecia (alopekia) is the term for mange in foxes. Hair loss can be caused by any number of conditions, reflected in a specific diagnosis.
Alopecia can be caused by many factors from genetics to the environment. While androgenetic alopecia (male or female pattern baldness, AGA for short) is by far the most common form of hair loss, dermatologists also see many people with other forms of alopecia. Several hundred diseases have hair loss as a primary symptom.
Probably the most common non-AGA alopecias a dermatologist will see are telogen effluvium, alopecia areata, ringworm, scarring alopecia, and hair loss due to cosmetic overprocessing. Other, more rare forms of hair loss may be difficult to diagnose, and some patients may wait months, even years for a correct diagnosis and undergo consultation with numerous dermatologists until they find one with knowledge of their condition. Plus, with rare diseases, there is little motivation for research to be conducted and for directorys to be developed. Often, even when a correct diagnosis is made, a dermatologist can offer no known directory for the condition.
Research into hair biology and hair diseases is a very small field, and even research on androgenetic alopecia is quite limited. Perhaps 20 years ago there were fewer than 100 people worldwide who studied hair research in a major way. In recent years, there may be five times as many. This is still a small number compared to, say, diabetes research, but the expanding numbers of researchers investigating hair biology is positive, and eventually should lead to a better understanding and more help for those with rare alopecias.
Some hair loss conditions go by the name “effluvium,” which means an outflow. Effluviums characteristically affect different phases of the hair growth cycle.
Hair follicles on the scalp do not continuously produce hair. They cycle through a growth stage that can last two or more years, then regress to a resting stage for up to two months before starting to grow a new hair fiber again. At any time on a healthy human scalp, about 80% to 90% of the hair follicles are growing hair. These active follicles are in what is called the anagen phase. That leaves up to 10% to 20% percent of scalp hair follicles in a resting state called telogen, when they don’t produce any hair fiber.
Telogen effluvium (TE) is probably the second most common form of hair loss dermatologists see. It is a poorly defined condition; very little research has been done to understand TE. In essence though, TE happens when there is a change in the number of hair follicles growing hair. If the number of hair follicles producing hair drops significantly for any reason during the resting, or telogen phase, there will be a significant increase in dormant, telogen stage hair follicles. The result is shedding, or TE hair loss.
TE appears as a diffuse thinning of hair on the scalp, which may not be even all over. It can be a bit more severe in some areas of the scalp than others. Most often, the hair on top of the scalp thins more than it does at the sides and back of the scalp. There is usually no hair line recession, except in a few rare chronic cases.
The shed hairs are typically telogen hairs, which can be recognized by a small bulb of keratin on the root end. Whether the keratinized lump is pigmented or unpigmented makes no difference; the hair fibers are still typical telogen hairs.
People with TE never completely lose all their scalp hair, but the hair can be noticeably thin in severe cases. While TE is often limited to the scalp, in more serious cases TE can affect other areas, like the eyebrows or pubic region.
Whatever form of hair loss TE takes, it is fully reversible. The hair follicles are not permanently or irreversibly affected; there are just more hair follicles in a resting state than there should normally be.
There are three basic ways TE can develop.
There might be an environmental insult that “shocks” the growing hair follicles so much that they decide to go into a resting state for a while. This results in an increase in hair shedding and a diffuse thinning of hair on the scalp. This form of TE can develop rapidly and may be noticeable one or two months after receiving the shock. If the trigger is short lived, then the hair follicles will return to their growing state and start producing new hair fibers pretty quickly. This form of TE usually lasts less than six months and the affected individual has a normal scalp hair density again within a year.
The second form of TE develops more slowly and persists longer. The hair follicles may not all suddenly shed their hair fibers and enter a resting telogen state. Rather, the follicles may enter a resting state as they normally would, but instead of returning to a new anagen hair growing state after a month or two, they stay in their telogen state for a prolonged period of time.
This results in a gradual accumulation of hair follicles in a telogen state and progressively fewer and fewer anagen hair follicles are left growing hair. In this form of TE, there may not be much noticeable hair shedding, but there will be a slow thinning of the scalp hair. This form of TE is more likely to occur in response to a persistent trigger factor.
- In a third type of TE, the hair follicles do not stay in a resting state but rather cycle through truncated growth cycles. When this happens, the individual experiences thin scalp hair and persistent shedding of short, thin hair fibers.
Resourced from www.americanhairloss.org