Abstract
It has been shown by previous workers that 4-pyridoxic acid is a predominant vitamin B_6 metabolite excreted in urine. By the modified method of Huff, Pertzweig and Sarett(flrorescence method using microphotometer)we have measured the 24 hour urinary excretion of 4-pyridoxic acid in patients of various diseases. The 24 hour excretion following an injection of 30 mg of vitamin B_6 was significantly lower in patients with nephritis, pancreatitis and hepatitis. Antabuse was found to inhibit oxidation of pyridoxal to 4-pyridoxic acid both in vivo and in vitro, but the urinary excretion after injection of pyridoxine and pyridoxamine was not reduced by antabuse. This suggests that pyridoxal is chiefly converted to 4-pyridoxic acid by aldehyde oxidase, but most of pyridoxine and pyridoxamine are converted to 4-pyridoxic acid in some other manner.
