The relationship between plasma and red cell concentrations of vitamins thiamine diphosphate, flavin adenine dinucleotide and pyridoxal 5-phosphate following elective knee arthroplasty

Background & aims: Water soluble vitamins B1, B2 and B6 are essential precursors for a wide variety of coenzymes involved in intermediary metabolism and their status is usually assessed from blood samples. The aim of the study was to examine the relationship between plasma and intra-cellular B-vitamins following the systemic inflammatory response of surgery. Methods: Patients (n=10) who underwent an elective knee arthroplasty, had venous blood samples withdrawn pre-operatively and at 12, 24, 48, 72 and 168 h after the start of surgery for the analysis of circulating concentrations of C-reactive protein and albumin and also plasma and/ or red cell thiamine diphosphate (TDP), flavin adenine dinucleotide (FAD), pyridoxal 5-phosphate (PLP) as indicators of vitamins B1, B2, and B6 status respectively. Results: Pre-operative, baseline vitamin assessments were all within population reference ranges. Over the study period of 0–168 h there was a significant increase in circulating C-reactive protein concentrations (peak 48 h, P<0.001) and a significant fall in albumin concentrations (trough 48 h, P<0.001). Plasma FAD and PLP concentrations fell transiently (P<0.001) by approximately 40% reaching their nadir at approximately 48 h. Conclusions: The results of the present study indicate that plasma concentrations of FAD and PLP are transiently reduced following an inflammatory insult and therefore unlikely to be a reliable measure of status in the presence of a systemic inflammatory response. It may be that during such a response red cell concentrations provide a more reliable measure.