title: Urinary 4-pyridoxic acid excretion in 24-hour versus random urine samples as a measurement of vitamin B6 status in humans.
abstract: Urinary excretion of 4-pyridoxic acid (4PA) in 19 men (n = 5) and women (n = 14) was measured to evaluate the validity of determining the 4PA/creatinine ratio in random urine samples as an alternative to total 24-h 4PA excretion in assessing vitamin B6 nutritional status. The relationships among dietary vitamin B6 intake, 4PA excretion, plasma pyridoxal 5'-phosphate levels, and erythrocyte aspartate aminotransferase activity and in vitro stimulation by added plasma pyridoxal 5'-phosphate were examined. The subjects consumed all meals for 3 days in a metabolic unit, and protein intake was kept constant. Plasma pyridoxal 5'-phosphate concentration was positively correlated with vitamin B6 intake of the previous day (r = 0.61, p less than 0.01). There was a positive correlation (r = 0.59, p less than 0.01) between total 4PA and 4PA/creatinine in the 24-h urine samples. No difference (p greater than 0.05) in 4PA/creatinine between the 24-h samples and either morning or afternoon random samples taken the next day was found. These findings support the use of the 4PA/creatinine ratio in random urine samples as an alternative to 24-h urinary 4PA excretion.
mesh_terms: D000293:Adolescent; D000328:Adult; D001219:Aspartate Aminotransferases / Q000097:blood; D003404:Creatinine / Q000652:urine; D004912:Erythrocytes / Q000201:enzymology; D005260:Female; D006801:Humans; D007539:Isonicotinic Acids / Q000652:urine*; D008297:Male; D011732:Pyridoxal Phosphate / Q000097:blood; D011735:Pyridoxic Acid / Q000652:urine*; D011736:Pyridoxine / Q000008:administration & dosage*; D013048:Specimen Handling; D013997:Time Factors; D026681:Vitamin B 6 Deficiency / Q000175:diagnosis* / Q000652:urine
chemical_list: D007539:Isonicotinic Acids; D011735:Pyridoxic Acid; D011732:Pyridoxal Phosphate; D003404:Creatinine; D001219:Aspartate Aminotransferases; D011736:Pyridoxine