Hair Loss (Alopecia)

What Is Hair Loss?

Every person has 80,000 to 100,000 hairs on their head. Hair consists of keratins and is formed by hair follicles. A hair usually grows about 1 cm per month for three to six years. This growth phase is also called the anagen phase and varies in length from person to person and can last 10 years in people with very long hair, which is followed by a short transition phase (catagen) and a subsequent resting phase (telogen), during which the hair stops growing. This resting phase lasts two to four months. After that, the hair falls out, and new hair begins to grow in the hair follicle. Head hair is usually found in all stages of growth. It is, therefore, expected that hair falls out daily. A daily hair loss of up to 100 hairs is physiological. If more hair falls out, it is called increased hair loss (effluvium), which is often noticed when combing. Hair loss can also become noticeable through bald spots (alopecia).

Androgenetic Hair Loss in Women and Men

The most common type of hair loss is common hereditary hair loss androgenetic hair loss. About 50 to 70 percent of all men are affected. The typical hair loss is evident, starting at the forehead hairline (receding hairline) and parting hair. The hair at the back of the head and the lower temple are not affected. Usually, the hairs begin to fall out between the ages of 20 and 30. Not only men are affected by androgenetic hair loss, but also 25 to 40 percent of women. Unlike in men, hair loss typically appears in the hair's parting and does not begin until menopause.

Diffuse Hair Loss

When hair falls out all over the head, this is called diffuse hair loss. The hair generally appears thinner, the scalp shines through, but no single bald spots are visible. There are two forms of diffuse hair loss: the late-type occurs two to four months after a triggering event (for example, taking medication). Within 6 to 12 months, the hair grows back densely. The early type of hair loss occurs after severe damage to the hair follicles. The hair falls out a few days later. Again, the hair grows back, often denser than before.

Circular Hair Loss

Circular hair loss (alopecia areata) is the third most common form of hair loss after androgenic and diffuse hair loss. About 1 to 2 percent of people suffer from it once in a lifetime. Mainly children and young people under 30 years of age are affected. Circular hair loss usually occurs suddenly with an initial round hairless spot. Later, hair loss can spread from this area or occur in several places. There are many variants of circular hair loss. Small areas where the hair grows back spontaneously can appear, and several hairless areas or years of complete hairlessness.

Atrophying Alopecia

Besides, there is also scarring and atrophying alopecia. These include a group of different diseases that lead to the irreversible destruction of hair follicles. Folliculitis decalvans is a persistent inflammation of the scalp with scarred hairless areas. Folliculitis et perifolliculitis capitis abscedens et suffodiens occurs almost exclusively in men and is characterized by inflammatory bald regions. Small patches of hairless regions develop in the case of lichen ruber follicular; they are often not noticed for years. Due to the hair follicles' excessive keratin formation (hyperkeratosis), a "white border" is formed around the individual hairs in the affected areas. At the same time, changes in fingernails and toenails can also occur. Postmenopausal frontal fibrillating alopecia (Kossard) is a variant of Lichen ruber follicullaris and mostly affects older women. The hair falls out mainly on the forehead, almost always together with the eyebrows.

What Are the Causes of Hair Loss?

In androgenetic hair loss in men, male sex hormones (androgens) influence hair growth. It is not, as is often assumed, an excessive production of sex hormones that leads to hair loss, but a congenital hypersensitivity of the hair follicles to androgens. Dihydrotestosterone (DHT) is formed when testosterone is broken down. Hair follicles have receptors for dihydrotestosterone. The dihydrotestosterone receptors on the hair follicles are increased and react more sensitively in androgenetic hair loss. When DHT binds to the receptors, the hair follicles become smaller, and the hair growth phase is shortened. In the final stage, the hair follicles shrink entirely.

The role of androgens (male sex hormones) in androgenetic hair loss in women is not yet as clear as in men. Hair loss in women typically occurs at the beginning of menopause. At this time, estrogen production in women decreases, and freer testosterone circulates in the blood.

Diffuse hair loss can have many different causes. Hair loss is caused by an event that damages the hair follicles. Late type hair loss is telogen hair loss (telogen effluvium): hair that is in the growth phase (anagen phase) enters the resting phase (telogen phase) prematurely due to damage. The hair does not fall out until after the two to four-month resting phase. Triggers can be, for example, feverish infections and certain infectious diseases, thyroid gland disease, wrong diets, iron, selenium, zinc or calcium deficiency, vitamin deficiency, medication, or stress. Hormonal changes after pregnancy or discontinuation of the contraceptive pill also trigger telogen effluvium. Diffuse hair loss of the early type damages the hair roots to such an extent that the hair breaks off when it reaches the skin's surface a few days later. The triggering event can be, for example, chemotherapy or a severe infection.

Circular hair loss is suspected to be caused by an autoimmune reaction. Immune cells (cytotoxic T-lymphocytes) damage the hair follicles, which causes the hair to fall out. It is unclear why only some areas are affected. It is also not yet clear what causes the immune reaction. Experts discuss mental strain and stress as triggers. The hairlessness disappears within six months in one-third of the patients. About 50 to 80 percent of the patients are free of symptoms after one year. The disease also occurs together with other inflammatory and autoimmune diseases.

In folliculitis decalvans, a bacterial infection (staphylococci) of the hair follicles causes inflammation of the scalp. The inflammation of the scalp in folliculitis et perifollicultits capitis abscedens et suffodiens is usually an inflammation without bacterial involvement. In lichen ruber follicular, immune cells (T-lymphocytes) accumulate in the scalp and hair follicles, which may be caused by a misdirected cellular immune response.

Treatment Methods: What Can Be Done About Hair Loss?

For the treatment of androgenetic hair loss, there are two effective active ingredients available for men. Minoxidil is applied to the scalp as a solution or foam. Finasteride is taken as a tablet and inhibits the conversion of testosterone into dihydrotestosestpsterone. Both drugs are very effective: treatment with Finestarid or Minoxidil stops hair loss in 80 to 90 percent of the patients; in about 50 percent, the hairs thicken again. As a side effect, the scalp may become red, flaky, and inflamed after applying Minoxidil. Men who take Finestarid may have erectile dysfunction and a decrease in desire for sexual intercourse. Finasteride occasionally leads to enlargement of the mammary glands (gynecomastia). Women can also treat hair loss with Minoxidil. But, Finasteride is not approved for women. Hormonal therapy with antiandrogens for women suffering from hormonal dysregulation is possible, and hair transplantation is suitable as a complementary measure for progressive hair loss. Aloe vera's effectiveness, ginkgo, food supplements, and many other remedies are not sufficiently scientifically proven!

The treatment of diffuse hair loss depends on the cause. If the causative disease is treated or the trigger removed, the hair grows back again.

In circular hair loss, it is recommended to wait until the hair loss is less severe. Often the hair grows back spontaneously. Patients can take zinc as support. Zinc works as an immunomodulator, and the intake has no side effects. If the circular hair loss needs treatment, the most effective treatment is immunotherapy with diphenylcyclopropenone or squaric acid dibutyl ester. The drugs are applied to the scalp and trigger an allergy there. The immune cells (T-lymphocytes) in the scalp react to the allergens and no longer attack the hair follicles. Depending on the disease's extent, the method is successful in 30 to 80 percent of cases. Alternatively, therapy with corticosteroids or triamcinolone crystals can be tried. There are many other therapeutic approaches, such as stimulation or laser therapy, but their effectiveness has not been sufficiently proven.

Folliculitis declavans caused by staphylococci infection is treated with antibiotics (for example, Clindamycin and Rifampicin) and germ reducing shampoos. The sterile inflammation in folliculitis et perifollicultits capitis abscedens et suffodiens can be treated with glucocorticoids and isotretinoin. In patients suffering from lichen ruber follicular, external application of corticosteroids or ingestion of hydroxychloroquine may relieve the symptoms.

Which Doctors Are Specialists in Hair Loss?

In the case of hair loss, the patient should first consult a dermatologist. Since hair loss is related to a disease or damage to the roots, and since the hair roots are located in the scalp, a dermatologist is the first professional to consult. Alternatively, the patient can consult an endocrinologist, especially if a hormonal cause is suspected. A gynecologist can help women if hormones are responsible for hair loss.

Literature:

Raab, W. (2012). Haarerkrankungen in der dermatologischen Praxis. Springer-Verlag

Wolff, H. Fischer, T., Blume-Peytav, U. (2016). Diagnostik und Therapie von Haar- und Kopfhauterkrankungen. Deutsches Ärzteblatt. Jg. 113, Heft 21

Hoffmann, R., Universitäts-Hautklinik Marburg (2004). Der Hautarzt. Springer-Verlag, online publiziert, 2004, 55:89–111

Umweltbundesamt (2005). Haaranalyse in der Umweltmedizin – Stellungnahme der Kommission „Human-Biomonitoring“ des Umweltbundesamtes. Bundesgesundheitsblatt - Gesundheitsforschung - Gesundheitsschutz 2005, 48:246–250, Springer-Verlag