title: Body protein index based on bioelectrical impedance analysis is a useful new marker assessing nutritional status: applications to patients with chronic renal failure on maintenance dialysis.
abstract: BACKGROUND
  Evaluation and monitoring of nutritional status is a fundamental concept in providing nutritional care to patients with end-stage renal failure. There have been, however, few practically available indices assessing whole body protein stores of patients.
  
  
  METHODS
  We enrolled 448 end-stage renal disease patients, 394 on maintenance hemodialysis (HD) and 54 on continuous ambulatory peritoneal dialysis (PD) in this study. 83 Age- and sex-matched subjects (controls) whose creatinine clearance was more than 70 ml/min and urinary protein excretion was less than 1.0 g/day were also recruited for comparison. To assess whole body somatic protein stores, we devised the body protein index (BPI). The volume of body protein mass was measured by multifrequency bioelectrical impedance analysis and then BPI was calculated as body protein mass (kg) divided by height in meters (m2). Based on BPI, we defined the nutritional status of the patients as normal if the value was within -10% of the mean value of control subjects, -10 to -14% as mild malnutrition, -15 to -19% as moderate malnutrition, and <-20% as severe malnutrition.
  
  
  RESULTS
  The required time for measurement was 5.2 +/- 1.3 min and coefficient of variation of measurements was 0.8 +/- 0.2%. Among men the mean BPI in both HD and PD patients was significantly lower than those of control subjects (4.25 +/- 0.37, 4.38 +/- 0.34 vs. 4.72 +/- 0.37 kg/m2, p < 0.001). In women, BPI was significantly lower in HD patients than in control subjects (3.65 +/- 0.34 vs. 4.00 +/- 0.34 kg/m2, p < 0.033), whereas only a nonsignificant lower tendency was found in PD patients (3.83 +/- 0.39 kg/m2, p = 0.067). There were no significant differences in BPI values between diabetic and non-diabetic subjects, both in men (4.26 +/- 0.41 vs. 4.25 +/- 0.36 kg/m2) and women (3.69 +/- 0.36 vs. 3.65 +/- 0.34 kg/m2). Based on BPI nutritional categories, 113 (28.7%) of all HD patients were classified as having mild malnutrition, 57 (14.5%) as having moderate malnutrition, 40 (10.1%) as having severe malnutrition, and 184 (46.7%) were classified as normal. The patients of longer dialysis history groups showed a tendency of lower BPI compared to those of shorter dialysis history groups (p < 0.05), although the ages of the patients of the two groups did not significantly differ. No correlations were found between BPI and serum albumin or transferrin concentrations. Only weak correlations were found with albumin in male and transferrin in female HD patients.
  
  
  CONCLUSIONS
  BPI calculated from measurement of multifrequency bioelectrical impedance analysis could evaluate whole body somatic protein stores, and is a potentially useful new marker assessing nutritional status in patients with chronic renal failure. Decreased body somatic protein stores, mainly due to muscle wasting, was prevalent in end-stage renal failure patients on maintenance dialysis.
authors: Department of Nephrology and Dialysis, Tokyo Medical University, Tokyo, Japan.
authors: Toshiyuki
authors: T
authors: Nakao
authors: Yoshie
authors: Y
authors: Kanazawa
authors: Yume
authors: Y
authors: Nagaoka
authors: Hideaki
authors: H
authors: Iwasawa
authors: Asako
authors: A
authors: Uchinaga
authors: Hiroshi
authors: H
authors: Matsumoto
authors: Tomonari
authors: T
authors: Okada
authors: Maki
authors: M
authors: Yoshino
mesh_terms: D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000378:metabolism; D001823:Body Composition / Q000502:physiology*; D017097:Electric Impedance; D005260:Female; D006801:Humans; D007676:Kidney Failure, Chronic / Q000150:complications / Q000503:physiopathology* / Q000628:therapy; D008297:Male; D008875:Middle Aged; D015596:Nutrition Assessment; D009752:Nutritional Status / Q000502:physiology*; D011502:Protein-Energy Malnutrition / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology; D006435:Renal Dialysis; D012709:Serum Albumin / Q000378:metabolism; D012727:Sex Characteristics; D014168:Transferrin / Q000378:metabolism
chemical_list: D015415:Biomarkers; D012709:Serum Albumin; D014168:Transferrin