Catalase, Glutathione Peroxidase, and Peroxiredoxin 2 in Erythrocyte Cytosol and Membrane in Hereditary Spherocytosis, Sickle Cell Disease, and Thalassemia Rapid and effective protocol to measure glutathione peroxidase activity Bulletin of the National Research Centre Springer Nature Link Glutathione Peroxidase Protocol Assay for quantitative determination of glutathione and glutathione disulfide levels using enzymatic recycling method Nature Protocols 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