title: Total nitrogen and free amino acid losses and protein calorie malnutrition of hemodialysis patients: do they really matter?
abstract: OBJECTIVE
  Protein calorie malnutrition (PCM) in patients on hemodialysis (HD) is multifactorial; however, HD per se induces nutrient losses. The aim of the present study was to characterize the losses of total nitrogen (TN) and free amino acids (FAs) through the dialysate and to determine the relationship between this loss and PCM, food ingestion, and the characteristics of the hemodialyzer in patients on HD.
  
  
  METHODS
  In a prospective study, 21 patients submitted to low-flux HD 3 times a week were evaluated within a period of 6 months regarding nutritional status, dietary calorie and protein intake, and losses through the dialysate of TN, FA, and urea nitrogen (UN). The type, surface area and reuses (up to 12) of the dialysis membrane were determined on each occasion, and the adequacy of dialysis was estimated by Kt/V.
  
  
  RESULTS
  50% of the patients were considered malnourished, although the mean protein and energy intakes were similar for the malnourished and nourished patients. Mean TN losses through the dialysate were 16 g/session (60% UN). FA losses varied from 3.8 to 4.2 g/total volume. TN and FA in the dialysate did not differ significantly between malnourished and nourished patients. There was a positive correlation between membrane (polysulfone) area and TN (p <0.05) and ultrafiltrate volume and TN (p < 0.05), and a nonsignificant correlation between reuse of the dialysis membrane and TN.
  
  
  CONCLUSIONS
  TN and FA losses through the dialysate were similar for malnourished and non-malnourished patients on chronic HD, thus they do not act as indicators of nutritional status impairment.
authors.affiliation: Division of Nutrology, University Hospital, Faculty of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil. isoldaprado@yahoo.com.br
authors.forename: Isolda
authors.initials: I
authors.lastname: Prado de Negreiros Nogueira Maduro
authors.forename: Natacha Maria
authors.initials: NM
authors.lastname: Elias
authors.forename: Carla Barbosa
authors.initials: CB
authors.lastname: Nonino Borges
authors.forename: Gilberto João
authors.initials: GJ
authors.lastname: Padovan
authors.forename: José Abrão
authors.initials: JA
authors.lastname: Cardeal da Costa
authors.forename: Júlio Sérgio
authors.initials: JS
authors.lastname: Marchini
mesh_terms: D000328:Adult; D000368:Aged; D000596:Amino Acids / Q000032:analysis; D005260:Female; D015312:Hemodialysis Solutions / Q000032:analysis; D006801:Humans; D008297:Male; D008875:Middle Aged; D009584:Nitrogen / Q000032:analysis; D011446:Prospective Studies; D011502:Protein-Energy Malnutrition / Q000209:etiology* / Q000378:metabolism; D006435:Renal Dialysis / Q000009:adverse effects*
chemical_list: D000596:Amino Acids; D015312:Hemodialysis Solutions; D009584:Nitrogen