Effect of renal transplantation on serum oxalate and urinary oxalate excretion

Serum levels of oxalate are elevated in uremic patients on dialysis. The effect of living related donor kidney transplants on serum and urine oxalate levels was studied in 8 patients. Serum and urine oxalate levels were measured prior to transplant, on the day of transplant and daily for 5 days postoperatively, and the results compared to those in 11 normal subjects. All transplanted kidneys functioned immediately. Serum oxalate fell from 55 +/- 9 mumol/l (484 +/- 79 micrograms/dl) before transplant to 21 +/- 3 mumol/l (185 +/- 26 micrograms/dl) the day after transplant, and to 9 +/- 2 mumol/l (79 +/- 18 micrograms/dl) 72 h after transplant. Serum oxalate in normal subjects was 9 +/- 2 mumol/l (79 +/- 18 micrograms/dl). During the initial 24 h after transplant urine oxalate averaged 1,244 +/- 150 mumol/l (109.5 +/- 13.2 mg), but fell to levels not statistically different from normal by 72 h after transplant. Rapid clearance of oxalate after transplant leads to transient hyperoxaluria until normal levels of serum oxalate are reached.