Performance of iohexol determination in serum and urine by HPLC: Validation, risk and uncertainty assessment

Background: Determination of glomerular filtration rate plays an important role in nephrological practice. lohexol is a reference marker for glomerular filtration rate determination. It is available and safe. The aim of this study was to develop a simple, efficient and easy to use analytical method for the quantification of iohexol in serum and urine by high performance liquid chromatography and to thoroughly validate this method. Methods: The HPLC method was inspired from the method published by Krutzen. The e.noval software V2.0 (Arlenda, Liege, Belgium) was used to compute all validation results. Results: The validation results indicate that the method will give accurate and reliable results for serum values ranging from 12.95 to 1295 mu g/ml and for urine values ranging from 86.0 to 4144 mu g/ml. In routine practice, iohexol concentrations found in plasma after injection range from 40 to 600 mu g/ml. The expected urinary values are Much wider. One should not hesitate to dilute urine samples to fit with the validated range over 5000 mu g/ml. Conclusion: This is the first time that a reference method for the determination of GFR is validated with such a rigorous and thorough protocol. Contrary to other GFR markers, iohexol is now strongly validated from an analytical point of view. (c) 2008 Elsevier B.V. All rights reserved.