PDF) Optimal and stable conditions for the determination of erythrocyte glutathione reductase activation coefficient to evaluate riboflavin status Glutathione Reductase (GR) Assay Kit (ab83461) Abcam Whats the best blood test for riboflavin? , Unfortunately, the gold standard is the erythrocyte glutathione reductase activity coefficient EGRAC, but no one offers this. Some labs offer Serum glutathione reductase level as a disease activity biomarker in systemic lupus erythematosus: a single centre preliminary study Lupus Science & Medicine Decreased Glutathione Peroxidase Activity Secondary to Severe Iron Deficiency: A Possible Mechanism Responsible for the Shortened Life Span of the Iron deficient Red Cell ScienceDirect Glutathione Reductase (GR) Activity Assay Kit