5-alpha-reductase
noun
5-al·pha-re·duc·tase
variants:
also 5α-reductase \ ˈfīv-ˈal-fə-ri-ˈdək-ˌtās, -ˌtāz 
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Medical Definition of 5-alpha-reductase
: an enzyme that catalyzes the conversion of testosterone to dihydrotestosterone
Note: Drugs (such as finasteride) are sometimes used to inhibit 5-alpha-reductase in the treatment of benign prostatic hyperplasia. A deficiency of 5-alpha-reductase causes the genetic disorder 5-alpha-reductase deficiency.