Abstract
Primary hyperoxaluria type 1 (PH1) is a genetic disorder characterized by overproduction of oxalate and eventual kidney failure. Kidney failure is usually irreversible in PH1. However, in patients with PH1 homozygous for the G170R mutation (in which the glycine at amino acid 170 is replaced by an arginine), pyridoxine is an enzyme cofactor and decreases urinary oxalate excretion by reducing hepatic oxalate production. We report recovery from dialysis in 3 patients with PH1 homozygous for the G170R mutation in response to pharmacologic-dose pyridoxine treatment. Median age at initiation or resumption of pyridoxine treatment was 37 (range, 20-53) years, and median daily pyridoxine dose was 8.8 (range, 6.8-14.0) mg per kilogram of body weight. Duration of hemodialysis before recovery of kidney function was 10 (range, 5-19) months. Plasma oxalate concentration improved after recovery of kidney function. At a median of 3 (range, 2-46) months following discontinuation of hemodialysis, estimated glomerular filtration rate was 34 (range, 23-52) mL/min/1.73m(2), plasma oxalate concentration was 8.8 (range, 4.6-11.3) μmol/L, and urinary oxalate excretion was 0.93 (range, 0.47-1.03) mmol/d. Kidney function was maintained during a median of 3.2 (range, 1.3-3.8) years of follow-up. These observations suggest that kidney failure may be reversible in a subset of patients with PH1 homozygous for the G170R mutation treated with pharmacologic-dose pyridoxine.