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Clin Chim Acta. 1999 Feb;280(1-2):101-11.

A simple, sensitive and reproducible assay for pyridoxal 5'-phosphate and 4-pyridoxic acid in human plasma.

Author information

1
MRC Human Nutrition Research, Cambridge, UK. chris.bates@mrc-hnr.cam.ac.uk

Abstract

We describe a procedure for the measurement of pyridoxal 5'-phosphate and of 4-pyridoxic acid in human plasma samples. It is based on the conversion of pyridoxal 5'-phosphate to 4-pyridoxic acid 5'-phosphate by cyanide in alkaline medium, followed by a high pressure liquid chromatographic separation, with fluorescence detection at acid pH. The assay is robust, sensitive, linear over a wide range, reproducible, and simple to perform. Samples stored at -80 degrees C are stable. Satisfactory agreement was obtained with results from the tyrosine decarboxylase-based assay for pyridoxal 5'-phosphate, in two other laboratories. Plasma samples from a National Survey of older British people were analyzed, and reference intervals for plasma pyridoxal 5'-phosphate intervals were derived. From the lower 2.5 percentile of the reference group, taken as the lower cut-off of the normal range, ca. 20% of elderly men and 11% of elderly women in the UK showed evidence of biochemical deficiency.

PMID:
10090528
DOI:
10.1016/s0009-8981(98)00173-9
[Indexed for MEDLINE]

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