Catalyzes the conversion of 17-oxosteroids to 17beta-hydroxysteroids (PubMed:8075637, PubMed:16216911, PubMed:27927697, PubMed:26545797). Favors the reduction of androstenedione to testosterone (PubMed:16216911, PubMed:27927697, PubMed:26545797). Testosterone is the key androgen driving male development and function (PubMed:8075637). Uses NADPH while the two other EDH17B enzymes use NADH (PubMed:26545797, PubMed:8075637, PubMed:16216911). Androgens such as epiandrosterone, dehydroepiandrosterone, androsterone and androstanedione are accepted as substrates and reduced at C-17 (PubMed:16216911). Can reduce 11-ketoandrostenedione as well as 11beta-hydroxyandrostenedione at C-17 to the respective testosterone forms (PubMed:16216911, PubMed:27927697). a 17beta-hydroxy steroid + NADP(+) = a 17-oxo steroid + H(+) + NADPH NADP(+) + testosterone = androst-4-ene-3,17-dione + H(+) + NADPH 17beta-estradiol + NADP(+) = estrone + H(+) + NADPH 3beta-hydroxyandrost-5-en-17-one + H(+) + NADPH = androst-5-en-3beta,17beta-diol + NADP(+) 17beta-hydroxy-5alpha-androstan-3-one + NADP(+) = 5alpha-androstan-3,17-dione + H(+) + NADPH 3alpha-hydroxy-5alpha-androstan-17-one + H(+) + NADPH = 5alpha-androstane-3alpha,17beta-diol + NADP(+) 3beta-hydroxy-5alpha-androstan-17-one + H(+) + NADPH = 5alpha-androstane-3beta,17beta-diol + NADP(+) androst-4-ene-3,11,17-trione + H(+) + NADPH = 17beta-hydroxyandrost-4-ene-3,11-dione + NADP(+) 11beta-hydroxyandrost-4-ene-3,17-dione + H(+) + NADPH = 11beta,17beta-dihydroxyandrost-4-ene-3-one + NADP(+) Hormone biosynthesis; testosterone biosynthesis. Steroid metabolism. Testis. The disease is caused by variants affecting the gene represented in this entry. Belongs to the short-chain dehydrogenases/reductases (SDR) family. 17-beta-HSD 3 subfamily.