Introduction: Primary hyperoxaluria (oxalosis) is an inherited metabolic disorder caused by a deficiency of the liver-spesific enzym, peroxisomal alanine: glyoxylate aminotransferase characterized by increased production and urinary excretion of oxalate and glycolate that leads to urolithiasis, nephrocalcinosis and, renal failure. In addition, oxalate accumulation in extrarenal all tissues such as the bone, joints, soft tissues, eye, cardiovascular system can be seen. The disease presents in childhood or adolescence with reccurrent urolithiasis and progressive renal failure. Because metabolic defect is located in the liver, liver-kidney transplantation, either combined or sequential is the only curative option in severe cases. We report two children with primary oxalosis.

Case Reports: Case 1: A-8-year-old girl presented with reccurrent urinary tract infection. Computed tomography and ultrasonography of her kidney revealed medullary nefrocalcinosis and urolithiasis. Analysis of the removed ureteric stones showed mainly Weddellite type of calcium oxalate. Serum oxalate and glycolate levels and daily urine oxalate excretion were elevated. End stage renal failure was developed after 1 year and the patient was started on continuous ambulatory peritoneal dialysis. At the age of 10, she received liver transplatation from her mother and she received renal transplantation from her mother after 4 months of liver transplantation. Case 2: A-2-month-old boy was diagnosed as primary oxalosis at external hospital. End stage renal failure was developed and the patient was started on continuous ambulatory peritoneal dialysis. At the age of 3, he received liver transplantation from his father. Two months later, he was hospitalized for kidney transplantation from his father. While at this time, he had convulsion attack. Glasgow Coma Scale was found as three. Computed tomography of head revealed intracranial haemorrhage. Even though all of medical interventions, the patient was died.

Conclusions: Because of continuing enzyme defect and oxalate accumulation, only transplantation of kidney is insufficient treatment. Liver-kidney transplantation, either combined or sequential is the only curative surgery. The patients must be follow up clinically for accumulation of oxalate after transplantation by serum oxalate and glycolate levels, daily urine oxalate excretion levels.