抄録
Because of the recent use of a large quantity of vitamin C for pigment anomaly, a restudy on the excretion in urine of vitamin C was conducted laying stress on oxalic acid, its metabolites. Furthermore an investigation on the increase of oxalate calculus by experimentally inserting calculus in bladder of rats and administering vitamin C to them was also made. When a large amount of vitamin C was administered, in most cases (approximately 80 percent) vitamin C was excreted mainly as dehydroascorbic acid in urine. Remarkable increase of urinary oxalic acid was not observed with oral administration or intravenous injection of 3 g of ascorbic acid per day as compared with control, but with 9g oral administration oxalic acid increased by 20 to 30 mg. Since 3,4-diketogulonic acid increases according to increased doses of vitamin C, it can be said that decomposition of dehydroascorbic acid to 3,4-diketogulonic acid was accelerated, but it seems that further oxidation to oxalic acid would not be so conspicuous. The amount of radioactive oxalic acid in urine, after the administration of ascorbic acid-1^<14>C, was 1 to 1.5 percent of doses in animals and 0.16 percent in men or 0.3 to 0.7 mg or 3 mg, respectively. In rats which were administered with 500 μg per day for 17 days by intramuscular injection, increase of the calculus was noted. In this case, oxalic acid in calculus was 0.733 mg as compared with 0.326 mg in the control group.
