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Kidney Week

Abstract: SA-PO429

Measuring Plasma Clearance for Exact Assessment of GFR: Multi versus Single Sampling

Session Information

Category: Chronic Kidney Disease (Non-Dialysis)

  • 308 CKD: Mechanisms of Tubulointerstitial Fibrosis

Authors

  • Ebert, Natalie, Charite University Hospital, Belgrade, Serbia
  • Schaeffner, Elke, Charite, Berlin, Germany
  • Pottel, Hans, KULeuven, Kortrijk, Belgium
  • Cavalier, Etienne, University of Liege, CHU Sart-Tilman, Liege, Belgium
  • Dubourg, Laurence, hospices civils de Lyon -Université Claude Bernard Lyon 1-INSERM U 820, LYON, France
  • Flamant, Martin, APHP, Paris, France
  • Delanaye, Pierre, University of Liège, Liège, Belgium
Background

Measurement of plasma clearance (PC) of iohexol or 51Cr-EDTA are both recognized as gold standard for exact GFR assessment. However, there are different protocols for PC measurement in terms of a varying number of plasma samples. We compare GFR results obtained from multi sample (MS) versus single sample (SS) PC measurement.

Methods

We used data from 4 European cohorts including indiv. with PC of iohexol (Liège, Lyon, Berlin) or 51Cr-EDTA (Paris). MS clearance was calculated using a one compartment model with 3 or 4 samples at 120, 180, 240 and 300 min (or longer) after injection and Bröchner-Mortensen correction. The SS PC was calculated using the Jacobsson method based on the preexisting estimated GFR. We studied concordance between both methods within ±10%.

Results

N=5,106 were included into the analysis with PC results based on 3 sampling points (120, 180 and 240 min) for slope calculation. Out of 5,106 indiv 657 had GFR results based on a 300 min (or longer) sampling period. In total 43% were females, mean age (SD) was 54 (±17) yrs, BMI 25.9 (±5.5) kg/sqm, mean GFR 65±26 mL/min (4-195 mL/min). Overall GFR results with SS at 120, 180 and 240 min had a concordance of ±10% with MS of 67, 84 and 91%, respectively. In the 657 individuals, highest concordance was observed with the 300 min sample if GFR <50 ml/min and with 240 min sample if GFR ≥50 ml/min (concordance within 10% was 96%, within 5% was 85%). Smallest concordance was found in individuals with very low GFR, at old age and with extreme BMI.

Conclusion

GFR results obtained from PC measurement with SS showed a high concordance with values from MS technique. This applies all the more if the timing for SS method was adjusted to estimated GFR. In conclusion, we found that in certain circumstances, i.e. epidemiological studies, SS iohexol PC measurement is an acceptable alternative to MS method.