LDHB is part of the lactate dehydrogenase family. LDHB is an oxidoreductase which catalyses the interconversion of pyruvate and lactate with concomitant interconversion of NADH and NAD+. LDHB catalyzes the oxidation of hydroxybutyrate, and frequently called Hydroxybutyrate Dehydrogenase(HBD). The LDH family consists of three members, LDH-A, LDH-B and LDH-C. LDHs function as powerful markers for germ cell tumors.