The relationship between plasma albumin, alkaline phosphatase and pyridoxal phosphate concentrations in plasma and red cells: Implications for assessing vitamin B6 status.

Autor: Talwar D; Scottish Trace Element and Micronutrient Diagnostic and Research Laboratory, Department of Clinical Biochemistry, Glasgow Royal Infirmary, Glasgow G4 0SF, UK. Electronic address: Dinesh.Talwar@ggc.scot.nhs.uk., Catchpole A; Scottish Trace Element and Micronutrient Diagnostic and Research Laboratory, Department of Clinical Biochemistry, Glasgow Royal Infirmary, Glasgow G4 0SF, UK., Wadsworth JM; Scottish Trace Element and Micronutrient Diagnostic and Research Laboratory, Department of Clinical Biochemistry, Glasgow Royal Infirmary, Glasgow G4 0SF, UK., Toole BJ; Scottish Trace Element and Micronutrient Diagnostic and Research Laboratory, Department of Clinical Biochemistry, Glasgow Royal Infirmary, Glasgow G4 0SF, UK., McMillan DC; University Department of Surgery, School of Medicine- University of Glasgow, Glasgow Royal Infirmary, Glasgow G31 2ER, UK.
Jazyk: angličtina
Zdroj: Clinical nutrition (Edinburgh, Scotland) [Clin Nutr] 2020 Sep; Vol. 39 (9), pp. 2824-2831. Date of Electronic Publication: 2019 Dec 13.
DOI: 10.1016/j.clnu.2019.12.012
Abstrakt: Background: Plasma concentrations of most vitamins decrease as part of the systemic inflammatory response (SIR). Thus low plasma values do not necessarily indicate deficiency. Vitamin B6 status is usually assessed by measurement of pyridoxal phosphate (PLP) in plasma, although vitamin concentrations in blood cells tend to be better markers of cellular stores. In health, plasma PLP appears to be determined primarily by intake, its binding to albumin, and its hydrolysis by alkaline phosphatase (ALP).
Objective: To examine, using in vitro studies, the effect of albumin concentration and ALP activity on PLP concentration in plasma and red blood cells of healthy subjects (HS) and critically ill patients (CI).
Design: Heparin and EDTA (ALP inhibited) whole blood samples from HS (n = 8) and CI (n = 26) were incubated with PLP. Concentration of PLP in plasma and red cells was measured. Albumin and ALP levels were determined in plasma.
Results: In PLP incubated heparin samples, there was a strong direct relationship between albumin in the concentration range 10-44 g/L and increase in plasma PLP concentration (r s  = 0.93, P < 0.001) and an inverse relationship with increase in red cell PLP concentration (r s  = -0.90, P < 0.001). In contrast, ALP activity was inversely associated with increase in plasma PLP concentration (r s  = -0.42; P = 0.013) and directly associated with red cell PLP concentration (r s  = 0.49; P = 0.003).
Conclusions: Plasma albumin concentration and to a lesser extent ALP activity influences PLP concentration in plasma and red cells. In conditions associated with low albumin (e.g. SIR) or altered ALP activity, red cell PLP measurements are more likely to be reliable than plasma measurements in differentiating true from apparent vitamin B6 deficiency and to guide vitamin B6 supplementation.
Competing Interests: Conflict of Interest The authors confirm that there is no conflict of interest. DT, DMCM conceived the idea of examining the relationship between albumin concentrations and plasma and red cell concentrations of pyridoxal phosphate and funded the study. BJT and DT collected, prepared and analysed the blood samples. DT, BJT, JW, AC and DMcM performed the statistical analysis. All authors contributed to the drafts and final version of the paper and are the guarantors.
(Copyright © 2019 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.)
Databáze: MEDLINE
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