Here, the determination of further urinary metabolites found in PH (glycolate in PH I, glyceric-acid in PH II and hydroxy-oxo-glutarate or dihydroxy-glutarate in PH III), analysis of plasma oxalate, the [13C2] oxalate absorption test, stool tests for Oxalobacter formigenes or even microbiota testing and finally genetic workup to detect variants in the different PH genes (AGXT-/GHPR-/HOGA 1) are possible diagnostic procedures [3, 4, 7, 19–22]. This evidence concerns the gene AGXT and primary hyperoxaluria type 3.