7alpha,12alpha-dihydroxy-5beta-cholestan-3-one + NADP(+) => 7alpha,12alpha-dihydroxycholest-4-en-3-one + NADPH + H(+)
7alpha,12alpha-dihydroxy-5beta-cholestan-3-one + nadp(+) => 7alpha,12alpha-dihydroxycholest-4-en-3-one + nadph + h(+)