BDH1 and Renal cyst: We analyzed PKD and normal human, mouse, and rat kidneys for crucial enzymes needed for the metabolism of BHB and found that the enzymes β-hydroxybutyrate dehydrogenase 1 (BDH1) and 3-oxoacid CoA-transferase 1 (OXCT1) were decreased in human and rodent PKD kidneys (Figure 4A), indicating possible impairment of BHB production and utilization by cystic kidneys.