Requires FAD. Renalase, previously thought to be a hormone, is a flavoprotein secreted into the blood by the kidney that oxidizes the 1,2-dihydro- and 1,6-dihydro- isomeric forms of ¦Â-NAD(P)H back to ¦Â-NAD(P)+. These isomeric forms, generated by nonspecific reduction of ¦Â-NAD(P)+ or by tautomerization of ¦Â-NAD(P)H, are potent inhibitors of primary metabolism dehydrogenases and pose a threat to normal respiration.