title: Calculation of Kt/V in haemodialysis: a comparison between the formulas.
abstract: BACKGROUND
  The quality of delivered dialysis can be measured by the Kt/V ratio, which can be calculated in various ways.
  
  
  OBJECTIVE
  To compare the Kt/V ratio obtained with the formulas of Lowrie (L) and Daugirdas (D) with the results measured by an Online Clearance Monitor (OCM).
  
  
  METHODS
  Observational, cross-sectional study of 59 patients on hemodialysis (HD). Data were collected in the same dialysis session (predialysis and postdialysis urea) and Kt/V was calculated by the OCM of the Fresenius 4008S machine (Fresenius Medical Care AG, Bad Homburg, Germany).
  
  
  RESULTS
  A total of 95 sessions were assessed, with a predominance of males 56% (33), and a sample mean age of 57 + 14 years. Hypertension (42%; n = 25), diabetes (12%; n = 7) and glomerulonephritides (8%; n = 5) were the most frequent causes of chronic kidney disease (CKD). Mean Kt/V values obtained with the L and D formulas and the OCM were 1.31, 1.41 and 1.32, respectively. Comparison between the L and D formulas showed a statistically significant difference (p = 0.008), with a Pearson's correlation of 0.950. The difference between the D formula and the OCM was also significant (p = 0.011 and r = 0.346), probably due to convective loss, estimated by the D formula but not by the OCM and L formula. The difference between the L formula and the OCM was not significant (p = 0.999 and r = 0.577).
  
  
  CONCLUSIONS
  These data suggest that the OCM can be used as a guide to the real-time adjustment of the dialysis dose.
authors.affiliation: Unidade de Hemodiálise do Hospital São Lucas da Pontifícia Universidade católica do rio Grande do Sul – HSL-PUC/RS; Unidade de Hemodiálise do Hospital de Clínicas de Porto Alegre. guilhermebreit@ hotmail.com
authors.forename: Guilherme
authors.initials: G
authors.lastname: Breitsameter
authors.forename: Ana Elizabeth
authors.initials: AE
authors.lastname: Figueiredo
authors.forename: Daiana Saute
authors.initials: DS
authors.lastname: Kochhann
mesh_terms: D003430:Cross-Sectional Studies; D054796:Drug Dosage Calculations; D005260:Female; D015312:Hemodialysis Solutions / Q000008:administration & dosage*; D006801:Humans; D008297:Male; D008875:Middle Aged; D006435:Renal Dialysis / Q000379:methods*
chemical_list: D015312:Hemodialysis Solutions