Effect of vitamin B6 administration on elevated plasma oxalic acid levels in haemodialysed patients.

Accumulation of oxalic acid resulting in elevated plasma levels is a common finding in uraemic patients. Since vitamin B6 is an important coenzyme in oxalic acid metabolism the influence of vitamin B6 administration on plasma oxalic acid levels was investigated. Vitamin B6 was administered to eight chronic haemodialysis patients with secondary hyperoxalaemia. Mean plasma oxalic acid concentration decreased from 149.5 +/- 67 mumol/l to 99.0 +/- 36.4 mumol/l within 2 weeks and to 93.8 +/- 33.1 mumol/l after 4 weeks of pyridoxine treatment (P less than 0.01) the mean reduction being 46% (32.0-56.1%). The decrease in plasma oxalic acid levels was most pronounced in patients with the highest pretreatment values. Two patients who received pyridoxine therapy prior to the beginning of the study had low initial values of plasma oxalic acid concentrations and showed no further decline.