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Updated: Oct 6, 2025
Assessment of Vascular Function in Patients With Chronic Kidney Disease
Published on: June 16, 2014
Comparison between different methods of calculating Kt/V as the marker of adequacy of dialysis
Fazl-E-Mateen1, Sajad Ahmad2, Irfan Elahi3
1Dr. Fazl-e-Mateen, FCPS. Assistant Professor, Department of Nephrology, Mayo Hospital, King Edward Medical College, Lahore, Pakistan.
Insights
Online clearance monitoring (OCM) can assess hemodialysis adequacy, but it slightly underestimates Kt/V compared to the Daugirdas formula and normogram methods. This finding aids in optimizing dialysis treatment effectiveness.
Area of Science:
- Nephrology
- Renal Replacement Therapy
- Biomedical Engineering
Background:
- Hemodialysis is a critical treatment for end-stage renal disease (ESRD).
- Accurate measurement of dialysis adequacy, specifically Kt/V, is essential for effective patient outcomes.
- Various methods exist to calculate Kt/V, each with potential variations in results.
Purpose of the Study:
- To compare the adequacy of hemodialysis using three distinct calculation methods: Daugirdas formula, normogram, and online clearance monitoring (OCM).
- To evaluate the correlation and agreement between these different Kt/V measurement techniques in ESRD patients.
Main Methods:
- An observational, quantitative study was conducted with 60 hemodynamically stable ESRD patients undergoing chronic hemodialysis.
- Kt/V values were calculated using the Daugirdas formula, normogram, and online clearance monitoring (OCM).
- Pearson's correlation and one-way ANOVA were employed to analyze the relationships between the measurement methods.
Main Results:
- Mean Kt/V values were 1.35 ± 0.33 (Daugirdas), 1.17 ± 0.29 (OCM), and 1.36 ± 0.33 (Normogram).
- A significant positive correlation (r = 0.897, p < 0.001) was found between all three methods.
- OCM demonstrated a tendency to slightly underestimate Kt/V compared to the Daugirdas formula and normogram.
Conclusions:
- Online clearance monitoring (OCM) is a viable method for assessing hemodialysis adequacy.
- While OCM shows strong correlation, it may slightly underestimate Kt/V values compared to traditional methods.
- These findings support the use of OCM, with awareness of its underestimation tendency, for monitoring dialysis effectiveness.
Objectives:
To compare different methods of calculating adequacy of hemodialysis in terms of Kt/V.
Methods:
This was an observational, quantitative study undertaken after the approval of Internal Review Board at the Hemodialysis Unit of Nephrology department, Mayo Hospital, Lahore from 1st December 2018 to 30th June 2019. Sixty hemodynamically stable patients of end stage renal disease undergoing hemodialysis for more than three months with age 18 to 70 years were included in the study by convenience non probability sampling. Critically ill patients with multiple co-morbidities like sepsis (i.e. total leukocyte count >11000 or <4000 x 109/L), ischemic heart disease, pace- makers, malignancies, cirrhosis etc. were excluded. Patients who were not adherent to dialysis prescription or hemodynamically unstable were also excluded. One way ANOVA and Pearson's correlation were used to find correlation between three methods of measuring Kt/V.
Results:
Mean ultrafiltration was 2.1+ 0.76 liter/session. Pre dialysis weight was 64.7 +14.7 kgs, mean post dialysis weight was 62.5 + 14.7 kgs. For every patient blood flow rate was 300 ml/m and dialysis flow rate was 500 ml/min. The mean values of Kt/V measured by Daugirdas formula was 1.35 ± 0.33, mean online clearance monitoring (OCM) value was 1.17 ± 0.29 and by normogram was 1.36 ± 0.33. There was positive significant correlation between values of Daugirdas formula, Normogram and online clearance monitoring (OCM) i.e. r = 0.897 (p-value < 0.001) measured by Pearson's correlation and one way-ANOVA.
Conclusion:
Online clearance monitoring can be used for measuring adequacy of hemodialysis, but OCM slightly underestimates Kt/V as compared to Daugirdas formula and Normogram.
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