Absorption of oxalic acid in rats by means of a 14C method

13 rats received a daily dose of 0.5 ml of a 1% solution of 14C-marked sodium oxalate (specific activity 29 nCi/ml) administered in one application with a throat probe. Feces and urine were collected every 24 h and the amount of 14C-oxalate was determined by liquid scintillation counting. The average distribution for 13 rats during 7 days showed 25.2% of 14C-oxalate in the urine and 73.4% in the feces. The rate of absorption is considerably higher than values given in literature (2.6--12% urine). These results indicate that in the pathogenesis of calcium oxalate stone formation some possible significance must be attributed to the exogenic oxalate.