GEORGE W. FRIMPTER, M.D., F.A.C.P.
A recent paper by Tada and associates (1) notes the remarkable effect of vitamin B6 in xanthurenic aciduria. Two mentally retarded siblings, children of first cousins, manifested excessive urinary excretion of xanthurenic acid, kynurenic acid, 3-hydroxykynurenine, and kynurenine after tryptophan loading. Laboratory study results, including normal serum B6 concentrations, gave no evidence of B6deficiency. Although the usual vitamin B6 requirement in childhood is 0.5 to 1.5 mg/day, Tada and colleagues found that much higher doses reduced the xanthurenic acid excretion to normal.
These studies were extended to an in vitro investigation of kynureninase in liver from one of the
GEORGE W. FRIMPTER. Pyridoxine (B6) Dependency Syndromes. Ann Intern Med. 1968;68:1131–1132. doi: 10.7326/0003-4819-68-5-1131
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Published: Ann Intern Med. 1968;68(5):1131-1132.
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