Ketone bodies (KBs) are an energy source utilised by mammals, the terminal oxidation of which (termed ketogenesis) is most active during fasting states or starvation. This process normally occurs in the mitochondria of cells. Cytoplasmic de novo lipogenesis and cholesterol synthesis are nonoxidative metabolic fates of ketone bodies. 3-hydroxybutyrate dehydrogenase type 2 (BDH2 aka DHRS6) is a cytosolic, tetrameric enzyme that may have a (as yet undetermined) physiological role in ketone body metabolism, either for energy supply or to generate precursors for lipid and sterol synthesis. The KB substrate (R)-3-hydroxybutyrate (3HBA) is dehydrogenated into acetoacetate (ACA) which can be further metabolised to acetyl-CoA (Guo et al. 2006).