Routine Determination of GFR in Renal Transplant Recipients by HPLC Quantification of Plasma Iohexol Concentrations and Comparison With Estimated GFR

Estimated glomerular filtration rate (e GFR ) methods are not sufficiently reliable in renal transplant recipients ( RTR ) and should be replaced by iohexol plasma clearance measurement. However, this method has poor availability in health centers. The aim of our study was to develop a high‐performance liquid chromatography ( HPLC ) method for plasma iohexol measurement in routine practice and to evaluate its plasma clearance as a reference of GFR . We developed an HPLC method using UV detection. We evaluated sample storage conditions to provide recommendations for routine practice. Then, we compared GFR based on plasma iohexol clearance ( GFR ‐iohexol) to e GFR using modification of diet in renal disease, C ockcroft and G ault, and CDK‐EPI equations in 40 RTR . The method was validated over a concentration range of 15–300 μg/l. Excellent linearity ( r > 0.998), inter‐ and intraday precision ( CV < 3.3%), and accuracy (>96.8%) were complied with ICH guidelines. We also demonstrated excellent samples stability (9 days). Although e GFR methods are not references in RTR , we found a correct concordance between e GFR and GFR ‐iohexol in our population. To conclude, our method is simple, rapid, accurate, and reliable for routine clinical and research use especially in RTR . J. Clin. Lab. Anal. 26:376‐383, 2012. © 2012 Wiley Periodicals, Inc.