Protein-energy malnutrition (PEM) and inflammation are common and usually concurrent
in maintenance dialysis patients. Many factors that appear to lead to these 2 conditions
overlap, as do assessment tools and such criteria for detecting them as hypoalbuminemia.
Both these conditions are related to poor dialysis outcome. Low appetite and a hypercatabolic
state are among common features. PEM in dialysis patients has been suggested to be
secondary to inflammation; however, the evidence is not conclusive, and an equicausal
status or even opposite causal direction is possible. Hence, malnutrition-inflammation
complex syndrome (MICS) is an appropriate term. Possible causes of MICS include comorbid
illnesses, oxidative and carbonyl stress, nutrient loss through dialysis, anorexia
and low nutrient intake, uremic toxins, decreased clearance of inflammatory cytokines,
volume overload, and dialysis-related factors. MICS is believed to be the main cause
of erythropoietin hyporesponsiveness, high rate of cardiovascular atherosclerotic
disease, decreased quality of life, and increased mortality and hospitalization in
dialysis patients. Because MICS leads to a low body mass index, hypocholesterolemia,
hypocreatininemia, and hypohomocysteinemia, a "reverse epidemiology" of cardiovascular
risks can occur in dialysis patients. Therefore, obesity, hypercholesterolemia, and
increased blood levels of creatinine and homocysteine appear to be protective and
paradoxically associated with a better outcome. There is no consensus about how to
determine the degree of severity of MICS or how to manage it. Several diagnostic tools
and treatment modalities are discussed. Successful management of MICS may ameliorate
the cardiovascular epidemic and poor outcome in dialysis patients. Clinical trials
focusing on MICS and its possible causes and consequences are urgently required to
improve poor clinical outcome in dialysis patients.