Abnormal over or under production of hormones can have a profound effect on hair follicle activity and the quality of hair produced. Even a temporary imbalance of hormone levels in the body can lead to anagen or telogen effluvium type hair loss. Hair growth is usually restored once the hormone levels have been returned to normal levels.

Hair follicles are particularly sensitive to concentrations of thyroid gland derived hormones. Thyroid hormones have a global influence on the cellular metabolism of proteins, carbohydrates, lipids and minerals. The cells of the hair matrix, due to their high degree of metabolic activity, are most profoundly influenced by the deficiency or excess of thyroid derived hormones.

Up to 50% of hypothyroid cases involve diffuse telogen effluvium type hair loss and occasionally anagen effluvium too. At first the hair loss is usually limited to the scalp but later, hair loss may spread to the eyebrows, chest, arms, and leg hair. Sometimes diffuse loss of pubic hair may also occur. Losing the outer one third of eyebrow hair is a distinctive symptom of hypothyroidism called “Hertoghe’s symptom” However, this symptom is only found in 25% of people who have hypothyroidism.

Sometimes, hair loss is the only apparent symptom of hypothyroidism and the dermatologist is the first to diagnose and treat the condition. Hair loss due to hypothyroidism is diagnosed with the help of blood tests to identify deficiencies in concentrations of thyroid stimulating hormone (TSH), thyroxin, and other thyroid gland controlled hormones.

Hypothyroidism can be controlled by providing patients with hormone supplements. When the hormone deficiency is successfully rectified, hair regrowth usually occurs although it may not be complete regrowth. Hormone supplements used to treat hypothyroidism can be synthetic manufactured drugs or naturally derived from animals. Some dermatologists claim the natural hormone supplements are superior for promoting hair regrowth.

Sometimes the onset of hypothyroidism promotes androgenetic alopecia. A drop in thyroid hormone production means a reduction of Sex Hormone Binding Globulin (SBHG) concentration in the blood. SBHG is important in reducing the activity of testosterone. With reduced SBHG levels, more testosterone is available for conversion to dihydrotestosterone and adverse impact on androgen sensitive scalp hair follicles. This may be another reason why some people have incomplete hair regrowth despite successful treatment of their thyroid hormone deficiency.

Up to 50% of individuals with hyperthyroidism develop diffuse telogen effluvium type hair loss. Most frequently the scalp hair is affected but body hair, including pubic hair, can become thin in some cases. The extent of hair loss is usually more limited than that observed in people with hypothyroidism. Remaining hair is often very fine, of poor quality and easily breakable. Sometimes an early symptom of hyperthyroidism is loss of pigment and early gray hair development.

Hair loss due to hyperthyroidism is diagnosed with the help of blood tests to identify any excess in concentrations of thyroid stimulating hormone (TSH), thyroxin, and other thyroid gland controlled hormones. If the hyperthyroid state is rectified with drug treatment and the thyroid hormones are returned to normal levels there can be reactivation of hair follicles, improvement in hair quality and complete hair regrowth.

The pituitary gland can act directly or indirectly on hair follicle activity. The pituitary gland produces growth hormones that have a direct impact on the cells in hair follicles. The pituitary hormones also influence the production of hormones made elsewhere in the body including; gonadotrophin, TSH and ACTH. These hormones in turn have an affect on hair follicle growth. In hypopituitarism one may see hair loss symptoms observed in other hormone deficiency diseases such as hypothyroidism.

A drop in pituitary hormone production results in very fine and dry scalp hair. The outer third of eyebrow hair can be entirely lost similar to that seen in hypothyroidism (called “Hertoghe’s symptom”). Men may have diffuse beard hair loss. Body hair can also be affected and may become very fine. Women in particular may almost entirely lose their pubic hair. Much of this hair loss is telogen effluvium where hair follicles have entered a prolonged inactive state due to lack of stimulation by hormones.

Pituitary hormone production abnormalities are observed in a variety of conditions including Sheehan’s syndrome, Simmond’s disease, and panhypopituitarism. There are several genetic conditions where an individual has no development of the pituitary gland. Pituitary dwarfism is the result as growth stimulating hormones are not being produced by the pituitary. Individuals with pituitary dwarfism may have persistent thin, dry, sparse hair. Arm pit, pubic, and beard hair fails to develop. Administering growth hormones to children with pituitary dwarfism can help increase body growth and hair follicle activity.