Fig. 1

Urinary, but not dietary oxalate levels differ between healthy controls and stone formers. A The approximate daily value of oxalic acid as measured through a diet history questionnaire was comparable between patient groups. HC (n = 14), SF (n = 64). B Urinary oxalate concentrations were determined with HPLC and normalized to creatinine levels. SF pre-operative urine had the highest oxalate concentrations (Kruskall-Wallis test with Dunn’s multiple comparisons). Data represent the median (line in box), IQR (box), and minimum/maximum (whiskers); HC (n = 29), SF (n = 83), SF-OR (n = 55)