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

Many methods have been used to assess the presence It is believed that malnutrition is common in patients with chronic renal failure (CRF). They have reduced of malnutrition in patients with CRF. A history of weight loss and symptoms such as anorexia, nausea body weight, depleted energy (fat tissue) stores, loss of somatic protein ( low muscle mass) and low levels of and vomiting may indicate impending or established malnutrition. Anthropometric measurements, such as serum albumin, transferrin, pre-albumin and other visceral proteins. Various studies show signs of malnumid-arm muscle circumference, skinfold thickness and hand-grip strength may all be useful tools for estimattrition in 23–76% of haemodialysis (HD) and 18–50% of peritoneal dialysis (PD) patients [1–4]. Such variing malnutrition. Hand-grip strength, in particular, has been shown to be an inexpensive, reliable and easily ations in the prevalence of malnutrition may be related to factors such as age, case mix, co-morbid conditions performed parameter of nutrition [4,8] that also predicts mortality in CRF patients (unpublished observaand quality of dialysis therapy. The aetiology of malnutrition in CRF is complex and may include many tion). Creatinine kinetics have also been advocated as a method to assess nutritional status. However, recent factors, e.g. poor food intake because of anorexia, nausea and vomiting due to uraemic toxicity, hormonal evidence suggests that it is unreliable in individual CRF patients [8,9]. More sophisticated methods used derangements, acidosis and increased resting energy expenditure. to evaluate nutritional status include bio-electrical impedance, dual-emission X-ray absorptiometry While malnutrition by definition is caused by poor nutritional intake, laboratory or anthropometric meas(DXA), nuclear magnetic resonance, computerized tomography, total body potassium and total body urements are generally used to define it clinically. Other factors can cause the same changes in body and plasma nitrogen, but mostly as research tools. Finally, several biochemical markers [e.g. serum albumin, pre-albumin, protein composition, especially inflammatory and infectious complications [5,6 ] and chronic heart failure insulin-like growth factor-1 (IGF-1) and transferrin] have been used to evaluate nutritional status. Of these (CHF). In addition, factors directly associated with the dialytic procedure, such as bio-incompatibility, biochemical markers, serum albumin so far has been the most common to assess malnutrition, and hyponutrient losses in the dialysate and, during PD, poor appetite due to abdominal discomfort and uptake of albuminaemia has sometimes, perhaps erroneously (see below), been used to diagnose malnutrition [10]. 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 Protein and energy requirements in chronic renal inflammatory response. However, since malnutrition failure also occurs in pre-dialysis patients [7], it is evident that dialysis-unrelated factors, e.g. infectious and The protein requirements in maintenance dialysis inflammatory complications as well as co-morbidity, patients are not well defined. It can be assumed that may also be important contributors to malnutrition the variation in protein requirements is much greater in CRF. among dialysis patients than in healthy subjects, due to additional causes of variation, such as endocrine Correspondence and offprint requests to: Peter Stenvinkel, MD, and biochemical abnormalities, anaemia, drugs, physDepartment of Renal Medicine, K56, Huddinge University Hospital, S-141 86 Huddinge, Sweden. ical inactivity and co-morbid conditions, e.g. cardiovas-