Submitted to: Clinical Chemistry
Publication Type: Peer reviewed journal
Publication Acceptance Date: 7/1/2005
Publication Date: 11/1/2005
Citation: Graham, J.M., Peerson, J.M., Haskell, M.J., Shrestha, R.K., Brown, K.H., Allen, L.H. 2005. ERYTHROCYTE RIBOFLAVIN FOR THE DETECTION OF RIBOFLAVIN DEFICIENCY IN PREGNANT NEPALI WOMEN. Clinical Chemistry. 51:2162-2165, 2005. Interpretive Summary: Riboflavin deficiency is very common worldwide, especially where intake of animal source foods is low. The most common assay for riboflavin status is based on the stimulation of the enzyme erythrocyte glutathione reductase in erythrocytes when flavin adenine mononucleotide (FAD) is added (the erythrocyte glutathione reductase activation coefficient, EGRAC). In this article we compare values for the EGRAC test with the direct measurement of the amount of riboflavin (the sum of flavin mononucleotide, FMN and FAD) in erythrocytes. Samples were from 84 pregnant women in Nepal where riboflavin deficiency is common. A cutoff for riboflavin deficiency was set at 170 nmol/L based on the 5th percentile of healthy Californians, and was shown to have good sensitivity and specificity for detecting the women with abnormal EGRAC values. Although the two methods gave comparable estimates of the prevalence of riboflavin deficiency, our method has several advantages including the ability to process samples twice as fast with less intra-subject variability, and less interference from glucose-6-phosphate dehydrogenase deficiency and B-thalassemia.
Technical Abstract: Riboflavin deficiency is common amoung chronic alcoholics, the elderly, and veatarians (1-4), but intake in the United States is generally adequate. (5,6), unlike the widespread deficiency in regions of the world with limited animal food sources (7,8). Riboflavin status has been assessed from measurements in urine, plasma, and erythrocytes (9-11). The erythrocyte glutathione reductase activity coefficient (EGRAC) is the commonly used test and reflects the adequacy of riboflavin to support enzyme function (10). In this assay, the stimulation of erythrocyte glutathione reductase by FAD is measured in vitro, and a higher activitycoefficient reflects a larger amount of unsaturated glutathione reductase apo-enzyme resulting from lack of FAD. The EGRAC cutoffs (12) are based on observational studies in well-nourished American school children (n=431) and adult men (n=6)and a depletion - repletion study in Indian adults (n=8) (13-15). These cutoffs are usually >1.4 for deficiency status, 1.2 to <1.4 for marginal status, and <1.2 for acceptable status.