5α-Dihydrotestosterone (5α-DHT) is the most potent androgenic steroid and is the main intracellular androgen. In target tissues such as the prostate, seminal vesicles and skin, testosterone is reduced to 5α-DHT by the enzyme 5α-reductase.
Its measurement (and the ratio of DHT to testosterone) is useful to identify end organ insensitivity to androgens due to 5α-reductase deficiency. This can be done in a random sample or in response to an hCG stimulation test.
Females up to 1 nmol/L
Serum (red top, plain tube) or plasma