The relationship between plasma and red cell B-vitamin concentrations in critically-ill patients

Abstract

Background and aims: Low vitamin B-complex status has been associated with poorer outcome in critically-ill patients. However, these findings have been based on indirect methods. Using direct methods for assessing vitamin status, we examined the effect of B-complex vitamin supplementation by measuring plasma and red blood cell B1, B2 and B6-vitamin concentrations in critically-ill patients. Methods: Thiamine diphosphate (TDP), flavin adenine dinucleotide (FAD) and pyridoxal phosphate (PLP) concentrations were measured in plasma and red cells of normal subjects (n ¼ 49) and ITU patients (n ¼ 41). Results: Compared with the normal subjects, critically-ill patients had higher C- reactive protein and lower albumin concentrations (Po0:001). Also, plasma FAD and PLP were lower (Po0:001) and red cell concentrations of both were higher (Po0:01) in critically-ill patients. Critically-ill patients were grouped according to whether (n ¼ 23) or not (n ¼ 18) they had been supplemented with B-complex vitamins. Compared with non-supplemented group, the supplemented group had significantly higher red cell TDP and PLP concentrations (Po0:01). Plasma FAD and PLP concentrations did not differ significantly between the groups. Conclusions: The results of the present study suggest that direct measurements of red cell FAD and PLP are more responsive to supplementation than plasma measurements in the critically-ill patient.