An androgen is a steroid hormone whos primary function is to maintain the male characteristics in human beings.
The most important androgen is testosterone.
This hormone is present in high amounts in males and in a much lower amount in females. In males its secretion is mainly by the testicles, in females by the ovaries.
Males have approximately 8 times the amount of testosterone than females. Testosterone and DHT (dihydrotestosterone) are responsible for the male characteristics.
Testosterone produces increased muscle mass, lowering of the voice, sperm production, enlargement of the penis, and sex drive. These are known as the anabolic effects.
DHT is responsible for hair growth in the beard, and chest, acne, prostate enlargement, and baldness. These are known as the androgenic effects.
It is important to point out that androgenic hair loss can exist in woman but is more severe in men due to the higher levels of androgens.
Male pattern baldness is the most common form of hair loss and is known for affecting males beginning in their 20s by a receding hair line, thinning of the hair, and gradual loss of hair in the frontal region.
This type of hair loss is due to a genetic predisposition inherited by genes from both the mother and father.
When this gene is present our hair follicles have a strong sensitivity to androgens, primarily DHT. DHT accounts for about 5% of all our testosterone and is a much stronger form of testosterone which is responsible for male pattern hair loss and benign prostatic hyperplasia.
In order to comprehend how testosterone plays a role in hair loss it is necessary to understand its metabolism. Testosterone is metabolized into 2 very important hormones: estradiol and DHT.
The conversion to estradiol takes place mainly in the fatty tissue and in the testes. The conversion to DHT takes place in the skin and prostate. DHT has 3 times more affinity for androgen receptors which are present in hair follicles. The enzyme that converts testosterone to DHT is called 5 alpha reductase and constitutes the final step in testosterone metabolism.
The treatment options for male pattern baldness are based on the inhibition of the enzyme 5 alpha reductase.
Since it has been proven that the hormone DHT is responsible for this type of hair loss we can treat hair loss by inhibiting its conversion from testosterone to DHT. There are few FDA approved treatments for male pattern baldness that have been scientifically proven to be effective in stopping hair loss and restoring hair growth. They are Finasteride (Propecia), and Dutasteride (Avodart). Both of these treatments act in a similar way as synthetic 5 alpha reductase inhibitors, therefore impeding the formation of DHT. These treatments are also effective for benign prostatic hyperplasia. Both of these treatments have similar side effects and are primarily: decreased sex drive, impotence, erectile dysfunction, abnormal sex function, gynecomastia (enlargement of the breasts), pain in the testicles. These side effects are not common but when they do present they usually result in the patients suspension of the treatment.
Another FDA approved treatment for male pattern baldness is Minoxidil (Rogaine). This drug acts in a different way that is not well understood but has vasodilator properties which allow more blood to reach the hair follicle allowing an increased flow of nutrients. This treatment has also been proven to stop hair loss and possibly promote hair growth.
One thing worth mentioning about all treatments for hair loss is that once the patient discontinues treatment hair loss will occur again with in a period of a couple months.