Circular hair loss is also called Alopecia areata. This disease causes sharply defined, round, bald spots on the hairy scalp. The beard hair or other hairy parts of the body can also be affected.
These areas can increase over time or occur more frequently. Both sexes can be affected both in childhood and adulthood. Circular hair loss is the most common inflammatory hair loss disease with about 1.4 million affected persons in Germany.
Causes of circular hair loss
The cause of circular hair loss is assumed to be an autoimmune reaction of the body. In this case, the hair roots are falsely attacked by cells of the immune system, so that hair growth is hindered in the course of an inflammatory reaction and the hair finally falls out. Thus, over time, larger bald spots develop, but these can also grow back on their own.
In some cases, however, the areas can also become bald, which can eventually lead to the loss of all hair on the head (Alopecia totalis) or even all body hair (Alopecia universalis). In addition, a genetic predisposition for circular hair loss is also assumed, as 10-25% of those affected can observe similar cases in their own family. However, the exact cause of the disease has not yet been conclusively clarified.
Various trigger factors are discussed which could trigger the development of circular hair loss. These include stress, trauma, infections, allergies, pregnancy, the use of certain medications, and scalp injury. The thyroid gland is an important organ that produces the thyroid hormones and releases them into the bloodstream.
Disorders of this organ function can lead to a variety of changes in different metabolic pathways and thus cause symptoms. These include a change in hair structure or hair loss. An overactive thyroid gland, i.e. an excess supply of thyroid hormones, typically leads to hair loss.
However, this is not a circular hair loss, but a diffuse hair loss. The hair does not fall out in circumscribed areas, but becomes lighter overall. However, autoimmune thyroid diseases can actually be accompanied by circular hair loss.
An increase in certain autoantibodies, namely TPO antibodies and Tg antibodies, is observed. Autoantibodies are antibodies that are directed against the body’s own proteins and thus cause autoimmune diseases. Cortisone is not only an important endogenous hormone, but also a widely used drug.
It can have an effect on calcium metabolism and thus lead to calcium deficiency, especially if taken over a long period of time. If the calcium deficiency persists for a long time, this has a negative effect on hair growth. The hair simply does not grow any further or only hardly at all.
However, cortisone does not cause hair loss, especially circular hair loss. Fungal diseases can lead to various forms of hair loss. Such fungal infections of the hairy head are also called tinea capitis.
They affect people of all ages, but more often tinea capitis is found in children. The most common pathogen is the fungus Microsporum canis. It is often transmitted by cats and guinea pigs and leads to round hair loss on the scalp.
The areas are about the size of a coin and show a fine scale. With the help of drugs that kill the fungus (antimycotics), scarless healing and regrowth of the hair can be achieved. A distinction must be made between this and tinea capitis profunda, which leads to scarring, circular hair loss.
Fungal pathogens, such as Trichophyton verrucosum, cause painful hair loss, which is accompanied by a strong inflammatory reaction of the skin. Painful, weeping lumps and crusts are a typical side effect. General symptoms such as fever, fatigue and swelling of the lymph nodes are also characteristic of tinea capitis profunda.
