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Clinical Chemistry, Vol 35, 241-245, Copyright © 1989 by American Association for Clinical Chemistry
P Edwards, PK Liu and GA Rose
Biochemistry Research Laboratories, St. Peter's Hospital, London, U.K.
This relatively simple high-performance liquid chromatographic (HPLC) method for measuring all seven known forms of vitamin B6 in plasma from individuals supplemented with pyridoxine hydrochloride shows good analytical recovery (85-98%) and precision. Within-run and between-run CVs for plasmas supplemented with standards were 4% and 7%, respectively. The major forms of B6 found in unsupplemented plasma from normal subjects were pyridoxal phosphate and 4-pyridoxic acid, with pyridoxal just detectable. The HPLC procedure correlated well (r = 0.94) with a modification of an enzymatic method involving apotryptophanase (Anal Biochem 1972;45:567-76) for measuring plasma pyridoxal phosphate, and also (r = 0.94) with a routine method for determining 4-pyridoxic acid in urine (Clin Chem 1964;10:479-89). Elimination of pyridoxine from the plasma of both normal and hyperoxaluric individuals was shown to be very rapid, with half-lives (t1/2) of 45 and 40 min, respectively. Finally, we present evidence for the existence of two other forms of B6 and discuss the possibility of a new metabolic pathway in vitamin B6 metabolism.
The following articles in journals at HighWire Press have cited this article:
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  O. Midttun, S. Hustad, J. Schneede, S. E Vollset, and P. M Ueland Plasma vitamin B-6 forms and their relation to transsulfuration metabolites in a large, population-based study Am. J. Clinical Nutrition, July 1, 2007; 86(1): 131 - 138. [Abstract] [Full Text] [PDF]
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M. V. Bor, H. Refsum, M. R. Bisp, O. Bleie, J. Schneede, J. E. Nordrehaug, P. M. Ueland, O. K. Nygard, and E. Nexo Plasma Vitamin B6 Vitamers before and after Oral Vitamin B6 Treatment: A Randomized Placebo-controlled Study Clin. Chem., January 1, 2003; 49(1): 155 - 161. [Abstract] [Full Text] [PDF]
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F. Hadj-Saad, M. Lhuissier, and J.-C. Guilland Chronic Exercise Affects Vitamin B-6 Metabolism but Not Requirement of Growing Rats J. Nutr., June 1, 1997; 127(6): 1219 - 1228. [Abstract] [Full Text]
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