Radhakutty A, et al. - The purpose of this study is to evaluate whether patients with rheumatoid arthritis have perturbations in arginine metabolite concentrations that are reversed by low dose prednisolone. The outcome of this study suggests that the rheumatoid arthritis patients have higher concentrations of asymmetric dimethyl arginine (ADMA) and mono methyl arginine (MMA), inhibitors of endothelial function. Chronic, but not acute, prednisolone therapy is related to a lower ADMA concentration, proposing a salutary impact of long-term glucocorticoid treatment on endothelial function.