Body composition in patients on haemodialysis: relationship between the type of haemodialysis and inflammatory and nutritional parameters.

INTRODUCTION: Overweight and obesity are associated to a higher cardiovascular risk and mortality in the general population and conflicting findings exist in the dialysis population. Adipokines (Leptin, adiponectin) produced in adipocytes may play a role in that process, and inflammatory parameters (CRP, IL-6) may be markers for it. Nevertheless, obtaining dry weight is today one of the main aims of adequacy in dialysis because overhydration is a clear mortality predictor.

OBJECTIVES: The aim of this study was to analyse body composition using an impedance spectroscopy technique in patients on haemodialysis (HD): and evaluate overweight and overhydration prevalence and its possible relation with adipokines, inflammatory and nutritional parameters, HD technique (Conventional [CHD], on-line haemodiafiltration [OL-HFD]) and erythropoietin needs.

METHODS: In a cross-sectional observational study, a pre-HD multifrequency bioimpedance spectroscopy (BIS) was performed in the middle of the week on 77 HD outpatients: 56 CHD and 21 OL-HFD. Patients were considered overweight when Body Mass Index (BMI) was ≥25kg/m² and overhydrated when overhydration normalised for extracellular water was higher than 0.15l. Clinical and biochemical parameters were analysed and IL-6, leptin and adiponectin levels were determined. This information was analysed in overweight and non-overweight, regular and overhydrated patients and both HD techniques.

RESULTS: 50% of patients fulfilled overweight criteria and 21% were pre-HD overhydrated. Overweight patients had a superior fat and extracellular water content (P<.001). Leptin (P=.001) and CRP (P=.036) levels were higher and adiponectin levels were lower (P=.003). An inverse correlation did exist between BMI and lean mass (P=.01). Nutritional markers (prealbumin, albumin, total proteins, creatinine and transferrin) were related to lean mass (P=.05). Comparing both HD techniques, a lower fat content was observed in OL-HFD (P=.049) without overhydration differences. In the univariate analysis, age, fat, extracellular/intracellular water ratio, leptin, hipoadiponectinaemia, lower lean mass and CHD technique were predictors of overweight. In the multivariate analysis, hipoadiponectinaemia (OR: 0.86; IC: 0.76-0.98), lean mass (OR: 0.89; IC: 0.84-0.94) and OL-HFD technique (OR: 0.200; IC: 0.04-0.99) predicted the absence of overweight.

CONCLUSION: This observational study emphasises the high prevalence of overweight in the outpatient haemodialysis population, as long as overweight is related with fat and extracellular water. Furthermore, it is accompanied by higher inflammation and leptin levels and lower levels of adiponectin. The use of the OL-HFD technique is associated to less overweight and fat content. Bioimpedance may prove to be a valuable ally for decisions regarding weight changes in dialysis patients.