Are there two types of malnutrition in chronic renal failure? Evidence for relationships between malnutrition, inflammation and atherosclerosis (MIA syndrome)

Abstract

It is believed that malnutrition is common in patients with chronic renal failure (CRF). They have reduced body weight, depleted energy (fat tissue) stores, loss of somatic protein (low muscle mass) and low levels of serum albumin, transferrin, pre‐albumin and other visceral proteins. Various studies show signs of malnutrition in 23–76% of haemodialysis (HD) and 18–50% of peritoneal dialysis (PD) patients [1–4]. Such variations in the prevalence of malnutrition may be related to factors such as age, case mix, co‐morbid conditions and quality of dialysis therapy. The aetiology of malnutrition in CRF is complex and may include many factors, e.g. poor food intake because of anorexia, nausea and vomiting due to uraemic toxicity, hormonal derangements, acidosis and increased resting energy expenditure. While malnutrition by definition is caused by poor nutritional intake, laboratory or anthropometric measurements are generally used to define it clinically. Other factors can cause the same changes in body and plasma protein composition, especially inflammatory and infectious complications [5,6] and chronic heart failure (CHF). In addition, factors directly associated with the dialytic procedure, such as bio‐incompatibility, nutrient losses in the dialysate and, during PD, poor appetite due to abdominal discomfort and uptake of glucose may also contribute to what we define as malnourishment in CRF. These may exert their action either by direct nutrient loss or by triggering the inflammatory response. However, since malnutrition also occurs in pre‐dialysis patients [7], it is evident that dialysis‐unrelated factors, e.g. infectious and inflammatory complications as well as co‐morbidity, may also be important contributors to malnutrition in CRF.