what is 5ar enzyme
5a-Reductase (5AR) is the enzyme that catalyzes the conversion of (among others): 1  Testosterone â 5a-DHT. 2  Androstenedioneâ androsterone. 3  Cortisol â allo-tetrahydrocortisol.s early as 1986, it was suspected by some that 5a-DHT might be a primary contributing factor to prostate cancer growth. 15 5a-Reductase (5AR) is responsible for conversion of testosterone to 5a-dihydrotestosterone (5a-DHT).