POx concentrations (Panel A) were markedly increased on presentation (187 μmol/L), fell with frequent dialysis, but were persistently higher (30–52 μmol/L) than typically expected for a hemodialysis patient. On hospital day 27, an oxalate removal study was performed and a total of 1.03 mmol oxalate was removed after four hours of hemodialysis (Panel B). The first dialysate oxalate level was measured ten minutes after starting hemodialysis. The efficiency of oxalate removal progressively declined over the 4-hour session as the POx concentration fell, but POx increased to 31.0 μmol/L pre-dialysis the next morning on the day of hospital discharge (Panel A). Conversion factor for oxalate in mg/L to μmol/L, x11.1.