MIDDLE MOLECULES - TOXICITY AND REMOVAL BY HEMODIALYSIS AND RELATED STRATEGIES

Renal failure results in the retention of metabolites which may arbitr arily be grouped according to their molecular weight: low (<300 dalton s molecular weight), middle (300-15,000 daltons), and high (>15,000 da ltons). Opinion in respect to the relative importance of these groups varies. Initially it was thought that small molecules were important. In the mid-1970s, investigators identified the possible pathophysiolog ical role of middle molecules. However, since positive identification of such molecules was difficult, opinion has shifted back in favor of small molecules, and little attention, with the exception of beta(2) m icroglobulin, has been paid to middle molecules and their removal by h emodialysis and related therapies. In this review current knowledge re garding middle molecules identified as uremic toxins and their removal by hemodialysis and associated therapies are discussed.