Definition of metabolic syndrome in peritoneal dialysis.

Metabolic syndrome (MetS) is defined as a cluster of risk factors for type 2 diabetes and cardiovascular disease; it is also an independent risk factor for developing chronic kidney disease (CKD) in the general population. Therefore, CKD has many similarities and associations with MetS, and the individual risk factors constituting MetS-especially insulin resistance and glucose intolerance, hypertension, dyslipidemia, and obesity-are also common features of the early stages of CKD. In the later stages of CKD, uremia per se and uremic complications such as fluid retention, protein-energy wasting, inflammation, and oxidative stress further contribute to an increase in the prevalence of MetS in CKD patients. In addition, PD patients exposed to glucose-based PD fluids have an increased risk of developing metabolic complications. The broad use of MetS in clinical research has raised the awareness of the public and of individual patients concerning the value of lifestyle interventions. However, the definition and pathogenesis of MetS are still debated, and no standardized definition nor proven prognostic value has been established for MetS as a cluster of risk factors for diabetes or cardiovascular disease in PD patients. Furthermore, considering the paradoxical associations of some of the risk factors in MetS with decreased mortality, another set of risk factors-those specific to patients with uremia (for example, inflammation and malnutrition)-and the appropriate cut-off levels to individual MetS risk factors should be taken account at the same time. Also, the benefit of interventions targeting these risk factors should be clarified in further clinical studies.