Assessment of vitamin B1, B2 and B6 status by coenzyme activation of red cell enzymes using a centrifugal analyser.

Abstract

We describe a fully automated method for the assessment of vitamin B1, B2 and B6 status using a centrifugal analyser. The activation of the red cell enzymes transketolase, glutathione reductase and aspartate aminotransferase) by their respective coenzymes were measured in freshly prepared haemolysate. The enzyme catalytic activities in the sample were measured with (maximal activity) and without (basal activity) the coenzyme, and the percentage activation was calculated. The between run precision for red cell transketolase, glutathione reductase and aspartate aminotransferase were 8.5%, 10.3% and 9.5% respectively. When whole blood was stored at room temperature for 6 hours, red cell aspartate aminotransferase activity significantly decreased (n = 10, p less than 0.05). There were no significant changes in the activities of the other two enzymes. For a group of 30 healthy young subjects, the mean (standard deviation) values for the percentage activation of transketolase, glutathione reductase and aspartate aminotransferase were 11.9% (7.3), 35.1% (19.1) and 85.3% (18.0), respectively. The vitamin status of a group of 86 pregnant women was assessed by this method; 2.3%, 8.1% and 8.1%, respectively, of the pregnant women showed a higher percentage activation for transketolase, glutathione reductase and aspartate aminotransferase than that found in the young subjects. Both groups correlated well with respect to the basal activity and the percentage activation of each enzyme. Basal activity was inversely proportional to the percentage activation. It is therefore suggested that the basal activity can be used as a second criterion in the assessment of vitamin status.