Clinical studies and chronic kidney disease: what did we learn recently?

This article summarizes relevant clinical studies that recently were devoted to the role of uremic toxins in outcomes of patients with chronic kidney disease and uremia. We summarize observational data linking uremic toxins (phosphate, the dimethylarginines, uric acid, and several large peptidic middle molecules and protein-bound solutes) to outcomes in observational studies. Interventional studies that evaluate the impact of different removal strategies on uremic toxin concentration in end-stage renal disease are then summarized along with clinical outcome studies with different dialysis strategies. Finally, we focuse on interventions in chronic kidney disease patients who are not yet on dialysis. We conclude that although there are more and more data on how to better remove uremic toxins by dialysis and nondialysis strategies, convincing evidence of the impact of these strategies on hard outcomes is much scarcer.