dihydrotestosteroni

Dihydrotestosterone (DHT) is an endogenous androgenic steroid hormone formed from testosterone by the enzyme 5-alpha-reductase. It binds to the androgen receptor with higher affinity than testosterone and is a potent activator of AR-mediated gene expression in many tissues.

Production and metabolism: DHT is primarily produced in peripheral tissues such as the prostate, skin, and, to a lesser extent, the testes, via 5-alpha-reductase type 1 and type 2. It circulates at lower concentrations than testosterone, but tissue levels can be high where conversion occurs. DHT cannot be formed by aromatization and is eventually inactivated to smaller metabolites such as 3α-androstanediol and 3β-androstanediol before excretion, often after conjugation.

Physiological roles: DHT is essential for the masculinization of external genitalia during fetal development. At puberty, it contributes to the development of secondary sexual characteristics in tissues such as the skin, hair, and prostate. Sensitivity to DHT in hair follicles is linked to androgenetic alopecia, while DHT also promotes prostate growth and function.

Clinical significance and therapy: Elevated DHT levels or heightened tissue sensitivity are associated with conditions such as benign prostatic hyperplasia and androgenetic alopecia. Inhibitors of 5-alpha-reductase (for example, finasteride and dutasteride) reduce DHT production and are used to treat BPH and hair loss, though they may cause sexual side effects. DHT cannot be aromatized to estrogen, so it lacks estrogenic activity.