While there are many possible reasons why someone may show hair loss, such as chronic diseases, skin diseases, reactions to certain medicines, seasonality, stress, malnutrition, environmental pollution and other aspects of modern life, the greatest percentage of male hair loss is due to heredity.
The estimated rate of inheritance of male hair loss is 81%. This means that genetic factors contribute more to the risk of male baldness than environmental ones. Hereditary predisposition is the most powerful factor for hair loss in men as the genes largely determine whether a man will show male pattern hair loss, the latter’s age of onset, pattern and degree of progress.
The most common pattern of androgenetic alopecia is the frontal and temporal thinning, with a tendency to extend to the crown of the head. Over the years, the thin area on the crown of the head expands and in many cases ultimately unites with the front area. Hair loss with apparent thinning occurs in 25% of the male population by the age of 30 and in 50% by the age of 45-50.
Male hair loss mostly starts at the end of puberty and progresses rapidly in the ages between 20-30, while the shedding slows down after the age of 30-35. At older ages, hair loss is slowed down even further, following a path that coincides with the stabilization and gradual decline in levels of male hormones in the blood.
Men suffering from androgenetic alopecia inherit hair follicles that are genetically susceptible to the hormone dihydrotestosterone (DHT). Dihydrotestosterone (DHT) is a derivative or by-product of testosterone. Testosterone is converted to DHT by means of the enzyme 5-alpha-reductase, which enters the follicles, causes the latter’s shrink and eventually causes changes in the follicles’ function, suppressing their growth. The hair follicles that are sensitive to the DHT hormone become thinner and their lifespan is reduced, resulting in shedding of the hairs and reduced density on the scalp.
More specifically, the action of the hormone DHT shortens the anagen, thus the growing phase of the hairs and expedites the telogen phase, in which the development stops. This process weakens the hairs, ultimately resulting in shedding. Men who show the first signs of thinning usually have their hair density reduced not due to shedding, but due to the progressive thinning of hair.
The hair follicles gradually degenerate, the life cycle of the hair is shortened, and every new hair that is produced becomes increasingly thinner and weaker, with an ever shorter life span. This occurs at a speed that differs from one man to another, until the follicle reaches its final stage of degeneration, in which the hair appears thin and transparent like fluff.
The life cycle of hair comprises of: the anagen phase (in which hair growth takes place), the catagen phase (in which the hair stops growing and becomes detached from its root), the telogen phase (shedding). Hair loss occurs when the duration of the anagen phase becomes shorter and the hairs quickly pass into the telogen phase (telogen hair loss or telogen effluvium). In this case, the hair loss is diffuse, i.e. not located in a particular area, but spread over the entire scalp, causing reduction of the hair density and thinning of the hair strands. This form of hair loss can occur after giving birth, due to chronic infections or after administration of certain medications.
Other cases of hair loss are due to diseases of the scalp, such as fungal infections, folliculitis and other inflammations. Hair thinning can also be caused by malfunction of the thyroid gland (hypothyroidism, hyperthyroidism) and in hyperparathyroidism and other chronic diseases. Hair loss also occurs after chemotherapy, radiation therapy and certain medications, and in a number of chronic diseases. In these situations, hair loss subsides after identifying and eliminating the cause.
Especially in women, major hormonal changes such as pregnancy, lactation, menstrual disorders, polycystic ovarian syndrome, menopause, etc., can lead to severe hair loss which is reversible in most cases. Localised hair loss of a usually permanent nature may occur in cases of traumatic alopecia, caused by injuries or burns to the scalp, face or body.
The most common cause of male hair loss is inheritance which, in combination with the action of the derivatives of the male hormone testosterone and age, cause the so-called androgenetic alopecia or male pattern hair loss. The genes that cause androgenetic alopecia can be transmitted by both parents. In men, hair loss of this type usually starts from the forehead, the temples and the crown, while it is absent from the occipital region (back of the head).
The occipital region and the sides of the head remain constant throughout life and show no significant hair loss, even in old men, as the male hormones have no effect here. This region is called the ‛constant hair growth zone’ and serves as the main donor site of follicles for hair transplantation.
Women have the same hereditary predisposition for androgenetic alopecia as men, but in women of reproductive age, because of the effect of the female hormone oestrogen, the clinical onset of androgenetic alopecia with intense hair loss and apparent hair thinning is not very noticeable until the age of menopause.
Only a small proportion of women, about 10 to 15%, shows clinically visible hair loss. Androgenetic alopecia in women usually occurs as diffuse hair loss; complete loss of hair from one area is rarely observed. Hair thinning in case of women with androgenetic alopecia becomes more profound after menopause.
Complete loss of hair at specific locations can be seen in alopecia areata (spot baldness) and in scars (cicatricial alopecia), such as scalp injuries or burns. Hair loss and creation of cicatricial patches is also seen in follicular lichen planus and lupus erythematosus. Characteristic feature of these pathological forms of hair loss is that they can affect any area of the scalp, even the constant hair growth zone, and evolve in an erratic and unforeseeable manner.
These conditions may be localised, small-scaled and relatively stable, but in rare cases can take a global form; in some cases of alopecia areata, complete hair loss may occur not only on the area of the scalp, but also on face, on eyelashes or even on the entire body. The cases of pathological hair loss are much rarer than androgenetic alopecia and constitute less than 10% of all cases of alopecia.
The diagnosis of hair loss should always be performed by a qualified dermatologist. Key elements in the diagnosis of androgenetic alopecia are the post-puberty history of occurrence, the gradual thinning in specific areas, and the family history regarding hair loss and alopecia. At Advanced Hair Clinics, hair loss is diagnosed or confirmed with a trichogram, using a special microcamera and software.
The special diagnostic photographic imaging and digital analysis tool “Follysis” that is used in our clinic, is one of the most comprehensive and accurate tools for the diagnosis of hair loss and the monitoring of response to treatment, allowing accurate measurements of hair density and hair strand diameter in each area. Certain cases of hair loss, such as alopecia areata or cicatricial alopecia, may require special blood tests (hormonological tests, iron, vitamins, minerals, etc.) or a skin biopsy (punch biopsy) for the purpose of differential diagnosis.
Important causes of hair loss in today’s era is the quite stressful way of life as well as intense emotions, stress, exposure to a dusted and polluted environment, excessive exposure to solar UV radiation, frequent contact with sea or chlorinated water.
Malnutrition can aggravate hair loss, as a lack of protein, vitamins and minerals such as iron or zinc intensify the problem. A proper diet that includes protein and iron can reverse hair loss.
Traction hair loss caused by the excessive pulling of the hair due to various hairdressing and styling processes (e.g. ponytails, extensions, etc) can take place.