Primary oxalosis: clinical and biochemical response to high-dose pyridoxine therapy.

Although pyridoxine hydrochloride (vitamin B6) is known to reduce the endogenous production of oxalate in some individuals with primary oxalosis, the dose for a satisfactory trial of treatment is not established. We report two cases of primary oxalosis on a daily regimen of 1 g pyridoxine hydrochloride, in which 24-hr urinary oxalate excretion decreased by 60% and 70%, respectively, with corresponding clinical benefit. The responses have been sustained up to 2.5 yr in one case, and 20 mo in the other. In the patient with renal failure, serum creatinine decreased from 243 to 146 mumole/liter after 15 mo of treatment. The decrease in glycollic acid excretion in both patients was consistent with an increase of glyoxalate transaminase activity by the vitamin. Supranormal levels of erythrocyte glutamic oxaloacetate transaminase (egot) activity were observed during therapy, and these may be useful as a measure of the effective dose of pyridoxine.