Primary Hyperoxaluria - An update

The primary hyperoxalurias (PH) types I, II and III are autosomal recessive inherited defects of the glyoxylate metabolism leading to endogenous oxalate overproduction and hence strongly elevated urinary oxalate excretion (> 1 mmol/1.73 m(2) body surface area per day; normal < 0.5). Main primary symptoms of PH are recurrent urolithiasis and/or progressive nephrocalcinosis. This and chronic inflammatory processes often lead to early renal failure, at least in PH type I, and consequently to systemic deposition of calcium oxalate crystals, which makes it often a lethal multisystemic disease. Diagnosis is often missed or delayed until end-stage renal disease (ESRD) or even after isolated kidney transplantation has failed due to recurrent oxalosis. Even in the patient with early diagnosis, treatment options are scarce with high fluid intake and measures to increase urine solubility, e.g., alkaline citrate. In addition, pyridoxine treatment in PH I may reduce oxalate excretion in about a third of patients. In ESRD time on dialysis should be short to avoid overt systemic oxalosis. Transplantation methods are differing depending on the type of PH and the individual patients'course, but combined liver and kidney transplantation is the method of choice in PH I, whereas isolated kidney transplantation is performed in PH II. No patient with PH III has yet been reported to develop ESRD.