Dihydrotestosterone

Dihydrotestosterone (DHT) is a potent androgen derived from testosterone through the action of the enzyme 5-alpha-reductase, which is active in tissues such as the prostate, skin, and hair follicles. DHT binds to the androgen receptor with greater affinity than testosterone and is a key driver of androgenic gene expression in target tissues. Most of the biological effects of DHT are local to tissues where it is formed or concentrated.

In development, DHT is essential for the masculinization of external genitalia in the fetus. At puberty, it supports the maturation of the male genital tract, enlargement of the prostate, sebaceous gland activity, and the growth of facial and body hair. In both sexes, DHT contributes to androgenic effects in skin and hair.

DHT levels and activity are clinically relevant. Excessive DHT signaling is associated with androgenetic alopecia (male pattern hair loss), benign prostatic hyperplasia, and can influence the progression of prostate cancer. Deficiency of DHT, such as in 5-alpha-reductase deficiency, can result in undervirilization in genetic males. DHT cannot be aromatized to estrogen, which distinguishes its metabolism from testosterone.

Measurement of DHT is usually through plasma assays, but tissue DHT levels are more indicative of local activity. Therapeutic use of 5-alpha-reductase inhibitors (finasteride, dutasteride) lowers DHT production and is employed to treat BPH, male pattern baldness, and hirsutism; these agents can have sexual side effects.

Female physiology also involves DHT production, though typically at lower levels; it can influence androgenic traits and conditions when dysregulated.