Catalyzes the conversion of 17-oxosteroids to 17beta-hydroxysteroids in the presence of NADPH (PubMed:16216911, PubMed:27927697). Favors the reduction of androstenedione to testosterone (PubMed:16216911, PubMed:27927697). Testosterone is the key androgen driving male development and function (By similarity). Among further tested androgens epiandrosterone and dehydroepiandrosterone are accepted as substrates and reduced at C-17 (PubMed:16216911). Can also reduce 11-ketoandrostenedione as well as 11beta-hydroxyandrostenedione at C-17 to the respective testosterone forms (PubMed:16216911, PubMed:27927697). Cannot use androsterone and androstanedione as substrates (PubMed:16216911). a 17beta-hydroxy steroid + NADP(+) = a 17-oxo steroid + H(+) + NADPH NADP(+) + testosterone = androst-4-ene-3,17-dione + H(+) + NADPH 3beta-hydroxyandrost-5-en-17-one + H(+) + NADPH = androst-5-en-3beta,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. Expression shows strong sexual dimorphism. In female, highly expressed in ovaries, and at lower levels in skin muscle, eyes and liver (PubMed:16216911). In males, strongly expresseed in liver and at lower levels in testis, spleen, kidney, intestine and muscle (PubMed:16216911). Expressed in embryogenesis from sphere to 84 h post-fertilization. Belongs to the short-chain dehydrogenases/reductases (SDR) family.