What Is Uremia? Retention versus Oxidation

The uremic syndrome is characterized by the retention of a host of compounds which in healthy subjects are secreted into the urine by the healthy kidneys. These compounds disturb many physiologic functions, resulting in toxicity. However, many of the retained compounds as well as many of the pathophysiologic actions of the known retention solutes remain unknown. In this publication, we review recent information on uremic toxicity. Especially the difficulty to remove compounds, such as protein-bound compounds and larger molecules, seems to play a crucial role. New strategies enhancing their removal might be highly useful. Part of the retained compounds are the result of oxidative processes due to the inflammatory status of uremic patients; however, other compounds are not, and even the concentration of oxidative compounds will be further increased by disturbances of urinary clearance.