Interleukin/cytokine profiles in haemodialysis and in continuous peritoneal dialysis

The uraemic syndrome is a complex condition that results from the retention of 'waste' compounds that normally would be excreted into the urine or catabolized by the kidneys. In addition, inflammation has been implicated in symptoms associated with uraemia, including its role in the malnutrition-inflammation-atherosclerosis syndrome. Regarding vascular disease, traditional risk factors such as hypertension and gender do not seem to have the same significance in the uraemic population compared with patients without renal failure, and so the possibility has been raised that the uraemic toxins that result in the uraemic syndrome could play a role in this process. In this review, various questions are addressed regarding the involvement of cytokines in uraemia and the effects of dialysis membranes and fluids in patients receiving haemodialysis or peritoneal dialysis on cytokine levels. The effects of non-dialysis-related factors on levels of cytokines, mortality rates and other uraemic disorders are also discussed. It is concluded that cytokines are undoubtedly retained in uraemia, and that the loss of renal excretion almost certainly plays a key role in this process. Many cytokines have a pro-inflammatory role, probably resulting in a number of clinical events that are related to the increased morbidity and mortality of uraemic and haemodialysis patients. Any adjustment of the subtle balance between pro- and anti-inflammation by medical interventions should be conducted carefully because of an enhanced risk of serious infectious episodes. Bioincompatibility of dialysis techniques probably enhances the generation of cytokines as well as other uraemic toxins.