The breakdown of Hyp to glyoxylate requires the action of four enzymes: proline dehydrogenase 2 (PRODH2), Δ1-pyrroline-5-carboxylate dehydrogenase (P5CDH), aspartate aminotransferase (AspAT), and 4-hydroxy-2-oxoglutarate aldolase (HOGA). Glyoxylate can then be converted into either glycine by AGT or glycolate by GR. In individuals with PH, the pool of glyoxylate is large enough to allow LDH to convert it into oxalate. *Based upon the results of this study, we propose that the naming of the PRODH2 protein be changed to hydroxyproline dehydrogenase (HYPDH).