Skip to main content

Systemic citrate load during continuous renal replacement therapy is not negligible and can be predicted using indirect methods


Data on significance of systemic gain of citrate during continuous renal replacement therapy (CRRT) are missing. Direct citrate measurements are scarcely available. The quantification using a difference of unmeasured anions (UA) on the filter and the method using correlation between concentration of citrate (Cf) in effluent to the proportion of citrate flow to blood flow (Qc/Qb) were compared with the control exact methods.


A prospective controlled observational study was performed in a 20-bed general ICU. Patients on 2.2% acid-citrate-dextrose (ACD, n = 41) were compared with controls on unfractioned heparin (n = 17). All were treated with an Aquarius Baxter device on 1.9 m2 polysulfone filters. Samples were taken from a central venous catheter, ports pre filter and post filter and from dialysate/filtrate 24 hours after commencing with CRRT and 60 minutes later.


There were no significant differences (P > 0.05) between CVVH (n = 18) and CVVHDF (n = 23) in measured citratemias nor in systemic gain of citrate. The difference between post-filter and pre-filter UA correlated with difference of citrate concentrations (r2 = 0.66). Citrate gain was calculated as 31.5 ± 10.5 mmol/hour utilizing this relationship. Cf showed tight correlation with the Qc/Qb ratio (r2 = 0.72). Gain of citrate calculated as citrate input minus citrate removal (effluent flow × Cf) where the regression equation replaces Cf was 29.4 ± 7.2 mmol/hour. The first exact method used post-filter and pre-filter citrate concentrations multiplied by matching blood flows. Gain of citrate obtained by this method was 29.3 ± 11.0 mmol/hour. The second exact method deducted citrate removal (15.7 ± 5.9 mmol/hour) in effluent from citrate input (45.1 ± 8.8 mmol/hour) and produced a citrate gain of 29.3 ± 7.2 mmol/hour. Comparing two studied methods of citrate gain estimation with exact methods showed no significant differences (P = 0.5, Kruskal-Wallis ANOVA). Bland-Altman analysis showed no systematic bias in results.


Systemic load of citrate is not negligible and can be predicted without taking direct citrate levels. Proposed indirect methods showed reasonable accuracy in systemic citrate load estimation.

Author information



Corresponding author

Correspondence to M Zakharchenko.

Rights and permissions

This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit The Creative Commons Public Domain Dedication waiver ( applies to the data made available in this article, unless otherwise stated in a credit line to the data.

Reprints and Permissions

About this article

Cite this article

Zakharchenko, M., Balik, M., Otahal, M. et al. Systemic citrate load during continuous renal replacement therapy is not negligible and can be predicted using indirect methods. Crit Care 15, P129 (2011).

Download citation


  • Citrate
  • Continuous Renal Replacement Therapy
  • Exact Method
  • Polysulfone
  • Citrate Concentration