It's very common for men receiving testosterone treatments to have an increase in dihydrotestosterone (DHT) because the body doesn't always know what to do with the excess. This is why these patients often have increases in other hormones such as estradiol and DHT. DHT is five times more potent than testosterone and is mainly used in the prostate, skin, and hair follicles. Testosterone replacement therapy (TRT) is a common treatment option for men with low testosterone levels.
TRT increases testosterone levels, which can lead to an increase in DHT that causes hair loss. To counteract this, topical DHT blockers may be used. Both testosterone and DHT are androgens, but DHT binds to androgen receptors more strongly and stays longer than testosterone. Studies have shown that the duration of testosterone supplementation can be correlated with hair loss, as longer exposure to exogenous testosterone increases the risk of male pattern baldness.
The conversion of testosterone to DHT may not be mandatory, but it amplifies the effects of testosterone in tissues with high 5α-reductase activity, such as the prostate and skin. In adult men, testosterone and DHT may perform many androgenic functions interchangeably. People often think of testosterone as a virtual synonym for manhood, aggression and strength, but women also have testosterone. Men with benign prostatic hyperplasia who were receiving dutasteride and who had low testosterone levels were more likely to have sexual dysfunction than those with normal testosterone levels.
When you increase your testosterone levels by receiving a testosterone injection, applying a gel, or using a testosterone patch, you provide more testosterone for the enzyme alpha-reductase 5 to use for the conversion of testosterone to DHT. While testosterone itself doesn't cause hair loss, the use of testosterone can accelerate the progression of male pattern baldness. When circulating testosterone concentrations are low, the formation of intraprostatic DHT may be important in maintaining prostate growth.