Discussion of androgens and their roles in hair growth


Hair Structure
Female Pattern Baldness
Localized Hair Loss
Sudden Hair Loss
Causes of Baldness
Role of Heredity
Role of Androgens
Psychological Aspects
Treatment of Baldness
Selection of a Clinic
Counselling
Anti-androgen Therapy
Hair Transplantation
Follicular Hair Transplant


Home >> Role of Androgens in Hair Growth

Androgens, male hormones, play an important role in the hair growth cycle. They also play their role in female pattern baldness. They are natural or synthetic compound that stimulates or controls the development and maintenance of male characteristics in vertebrae. It binds androgen receptors.

Androgens are responsible for sex characteristics of men. They can turn into estrogens in some situations. Dihydrotestosterone (DHT) helps growth of hair in some areas of the body.

The main sources of androgens in women are adrenal glands and ovaries. Androgens such as dehydroepiandrosterone (DHEA) produced by the adrenal glands can be converted to testosterone by enzymes.

In men testosterone is the main precursor of DHT that is converted by the alpha 5 reductase type I and II enzymes. However, in women dehydroepiandrosterone (DHEA) from the adrenal glands is the key precursor of DHT and requires conversion by both alpha 5 reductase enzymes and hydroxysteroid hydrogenase isomerase enzyme.

Androgens interact with androgen receptors in forms of testosterone and DHT. Androgen receptors can directly interact with the testosterone or when testosterone is converted into DHT by the enzyme 5-alpha-reductase.

Testosterone has some effects in females like oiliness of hair, appearance of pubic hair and axillary hair growth. There are other effects as well like extension of pubic hair growth area to the thighs and growth of facial and chest hair. Testosterone also causes growth of hair above the lips in women. DHT is supposed to be a main factor in most cases of pattern baldness.

It is seen that a high level of androgens in women may lead to hirsutism, in which there is excessive growth of hair on body parts of women where they are not supposed to have hair.

There is a certain difference in male and female pattern baldness. There are different concentrations of androgen metabolizing enzymes and androgen receptors in hair follicles in women compared to men. These differences also play their roles in the pattern of baldness in men and women.

In the hair follicles of women cytochrome P-450-aromatase content is up to six times more concentrated compared to hair follicles in men. Aromatase enzyme is present in greater concentrations at the back of the scalp in women but there is only small amounts of aromatase present in any region of scalp of men. It is also seen that women have around 3 times less alpha-5-reductase type I or type II enzyme in their frontal hair follicles when compared to men. Androgen receptor content in frontal hair follicles in men is 40% higher compared to hair follicles in women.

Hormonal imbalance also plays its role in hair growth. It is seen that sudden hormonal changes when starting or stopping the use of contraceptives can play their role in promoting female pattern baldness.

The condition of human insensitivity to androgens is called Androgen Insensitivity Syndrome. It can result in hair growth related problems like reduced axillary and pubic hair.