Abnormal hair loss: types and causes

A person loses an average of 50 to 100 hairs per day. This is a natural process. The amount of hair you lose depends on your age, the growth cycle of your hair and how much hair you have on your head. People with fine hair have more hair and therefore lose more hair. In men, more and more hair gradually falls out after puberty and folding occurs after menopause. However, sometimes the hair loss is abnormal. There could be several causes for this. Each hair has a lifespan of just under 3.5 years. Hair grows in hair follicles (follicles), of which there are about 100,000 on the head at birth. As you get older, this number gradually decreases.

The three life stages of a hair

Each hair goes through three phases. The first phase, the growth phase, lasts about 3 years. During this period, hair grows an average of one centimeter per month. In an adult human, approximately 90% of the hair on the head is in the growth phase. In the last part of the growth phase, cell division slowly decreases and the base of the hair becomes increasingly thinner. In the short transition phase that follows, the hair stops growing and becomes less firmly in the hair follicle. After a few days to 4 weeks, the rest phase begins. At the end of this final phase, which lasts an average of 4 months, the hair falls out. At that point, the hair follicle has already produced new hair and the cycle repeats. A hair follicle is capable of producing a hair 10 to 30 times in a row.
During a large part of your life, the number of hairs that enter the resting phase and the number of hairs in the growth phase are in balance. The hair density therefore remains virtually the same. However , when the number of hair follicles decreases over your life, your hair becomes thinner. The hair loss usually happens gradually and is evenly distributed over the head. Abnormal hair loss occurs when more than 100 hairs fall out every day. There may be various causes for this.

The typical picture of androgenetic alopecia (classic male pattern baldness) / Source: David Lewis, Wikimedia Commons (CC BY-SA-3.0)

Male pattern baldness (androgenetic alopecia)

Androgenetic alopecia is the most common form of permanent hair loss. It is the ‘classic male pattern baldness’, which affects about 60% of men to a greater or lesser extent. However, it can also occur in women. This form of hair loss is hereditary and is caused by the sensitivity of the hair to a certain male hormone (DHT). This hormone ensures a shortened growth phase. The number of hairs in the growth phase and the resting phase is therefore no longer in balance and more hairs fall out than new ones grow. Ultimately, under the influence of the male hormone, the hair roots shrivel and new hair growth is no longer possible. The hair on top of the head and at the temples gradually falls out. The hairs on the side of the head and on the back of the head remain, creating the typical ‘crown’. In men with androgenetic alopecia, hair loss begins some time after puberty. The consequences of this form of baldness can be (partly) reduced with a hair transplant, skin reduction or medicines (minoxidil, finasteride).

Female Pattern Hair Loss (HVP)

Female pattern hair loss (HVP) is very similar to androgenetic alopecia. It causes hair loss on the crown and usually occurs in menopausal women. About half of menopausal women appear to suffer from HVP to a greater or lesser extent. Unlike male pattern baldness, complete baldness on the crown is virtually uncommon. The hair bunch becomes (much) thinner over a larger part of the crown over a number of years. The hair on the back of the head remains normal. Typical for HVP is that the front edge of the hair also remains largely present. The hair loss can sometimes worsen in bursts and then remain stable for a long time. The hair follicles become smaller and produce thinner and shorter hairs. The number of hairs in the growth phase also decreases. This means that the scalp can no longer be sufficiently covered and the hair looks thinner. Really noticeable hair loss does not occur very often with HVP. The development of HVP is hereditary. However, the exact cause is not clear. Most women with HVP have normal levels of male hormones. However, because this form of hair loss mainly occurs in menopausal women, it is likely that there is a hormonal cause. The condition is almost always completely harmless. The younger the age at which hair loss begins, the worse the course usually is. Treatment is not simple and generally has little effect. Sometimes hormone inhibitors (cyproterone) or hair growth stimulants (minoxidil) can help.

A sharply defined bald spot due to alopecia areata / Source: Abbassyma, Wikimedia Commons (Public domain)

Spotted hair loss (alopecia areata)

With alopecia areata, hair falls out in spots. The condition is usually limited to the head, but eyelashes, eyebrows, beard hairs and pubic hairs can also fall out. In 5 to 10% of people who suffer from alopecia areata, all the hair on their head falls out (alopecia areata totalis). 1 to 2% lose all body hair (alopecia areata universalis). Alopecia areata can affect men and women of any age, but is most common in young adults. The cause of this form of hair loss is most likely an autoimmune condition, in which the body sees its own hair as hostile and attacks it. Inflammation then occurs around the hair roots, as a result of which the roots can no longer do their work properly. Only misshapen, easily broken hairs are created. Eventually, hair growth stops completely at the spot. The condition is almost never accompanied by itching or pain. There also appears to be a link between the atopic syndrome (constitutional eczema, hay fever and asthma) and psoriasis and alopecia areata. The condition progresses differently for everyone. Most people suddenly develop round or oval bald spots. In about 80% of cases, the hair returns spontaneously within a few months to two years. Sometimes the new hairs have no pigment. If the condition occurs at a young age, keeps recurring, the hairline is also affected or if there is another autoimmune disease (for example vitiligo or certain thyroid diseases), the prognosis becomes worse. The chance that the hairs will grow back is then smaller. The bald spots can possibly be treated with corticosteroid cream or ointment or ditranol cream. If the alopecia areata is very extensive, PUVA light therapy or diphenciprone stimulus therapy is sometimes chosen. However, the results are not satisfactory for everyone.

Hair loss due to a disturbed hair growth cycle (telogen hair loss)

Sometimes an unusually large number of hairs enter the resting phase (telogen phase) at the same time and fall out. There is then a disruption of the hair growth cycle. The hair loss usually occurs spread over the scalp and is sometimes so severe that the scalp becomes clearly visible. However, there are no truly bald spots. Telogen hair loss is much more common in women than in men. Acute telogen hair loss is often triggered by a (physical) traumatic event. Examples of this are childbirth (most common), serious illness, high fever, general anesthesia, bleeding and a strict diet. Two to five months after the event, the hair falls out en masse. You suddenly find a relatively large amount of hair on, for example, the pillow, in the hairbrush or in the drain of the shower. However, in approximately 30% of people who suffer from acute telogen hair loss, no cause is found.
If the hair loss lasts longer than six months, it is referred to as chronic telogen hair loss. This form is mainly seen in women between the ages of 30 and 50. The best known causes are thyroid abnormalities, anemia (due to iron deficiency) and certain medicines (retinoids, blood thinners, beta blockers, thyroid inhibitors and cytostatics used in chemotherapy). Excessive use of nutritional supplements, such as vitamin A, can also lead to telogen hair loss. As well as some diseases of the pancreas, liver and kidneys. In about a third of people no cause is found. With the acute variant, hair loss usually stops on its own within three to six months. Hair growth almost always completely recovers after this. In chronic telogen hair loss, recovery generally occurs gradually once the cause has been found and can be treated. If no cause is found, hair loss often goes back and forth over a number of years. However, here too, spontaneous recovery often occurs after a long time. There is no known treatment that can accelerate hair growth.

Hair loss with scarring of the scalp (alopecia cicatricalis)

Alopecia cicatricalis (scarring alopecia) is the collective name for forms of baldness in which scarring occurs on the scalp. With most other forms of hair loss, the scalp remains intact. With alopecia atrophicans, so much damage occurs to the hair follicles that the stem cells are also lost. The hair follicle shrivels and disappears, making the hair loss permanent. Scarring can be caused by hereditary conditions, infections with bacteria, fungi or protozoa (for example syphilis or leishmania) or certain types of cancer (basal cell carcinoma, squamous cell carcinoma or lymphoma). But direct damage to the hair follicle due to radiation or burning or inflammation of the skin due to, for example, lichen planus, sarcoidosis or lupus erythematosus (an autoimmune disease) can also result in scarring of the scalp. A distinction is made between the primary and the secondary variant. In the first case, the process of hair loss begins in the hair follicle and there is a disease of the hair follicle itself. In the secondary variant, the hair follicle is damaged by external causes, such as deep burns, skin cancer and chronic skin infections. However, in most forms of alopecia cicatricalis it is not clear what causes the hair loss. Once scarring has occurred, the hair cannot grow back. Treatment should therefore start as soon as possible. Anti-inflammatory drugs (for example corticosteroids) or anti-malaria medications are often used for this. Alopecia atrophicans is relatively rare.

Severe hair loss due to trichotillomania / Source: Robodoc, Wikimedia Commons (Public domain)

Hair loss due to repeated pulling of the hair

Repeatedly pulling your hair (trichotillomania) or by wearing certain hairstyles (traction alopecia) can lead to hair loss. Trichotillomania often happens unconsciously, for example because you often twist your hair around your fingers. Occasionally the condition is the result of a psychiatric disorder. With traction alopecia, certain hairstyles cause constant pulling on the hair. Examples of this are tight braids (such as Rasta hairstyles), tightly tied ponytails and hairstyles that often use a curl set. The result of both conditions is a fairly sharply defined bald or sparsely hairy spot on the head. When the hair is no longer pulled, hair growth usually recovers completely. However, if the hair is pulled too often and for too long, the hair loss can be permanent. Especially when it always happens to the same hair roots.
Hair loss and baldness are common problems. If you have hair loss problems, you can contact all Dutch dermatologists. A number of dermatologists have even specialized in hair loss problems.

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