5a-reductases, also known as 3-oxo-5a-steroid 4-dehydrogenases, are enzymes involved in steroid metabolism. They participate in 3 metabolic pathways: bile acid biosynthesis, androgen and estrogen metabolism, and prostate cancer. There are three isoenzymes of 5-alpha reductase, which vary in different tissues with age.

5a-reductases, also known as 3-oxo-5a-steroid 4-dehydrogenases, are enzymes involved in steroid metabolism. They participate in 3 metabolic pathways: bile acid biosynthesis, androgen and estrogen metabolism, and prostate cancer. There are three isoenzymes of 5-alpha reductase, which vary in different tissues with age.