Method VALIDation and Evaluation of Non-radioactive Methods to Measure Glomerular Filtration Rate

This study is a single centre intervention study to compare two methods of determining the measured glomerular filtration rate (mGFR). Subjects who receive radioactively labeled iothalamate (125I) and hippuran (131I) within the framework of routine clinical care, will be co-administered iohexol. The primary trial endpoint is the mGFR when administered 125I-iothalamate and 131I-hippuran versus iohexol. By determining the mGFR using both iohexol and iothalamate in the same patients, a direct comparison of the two methods can be made in terms of their accuracy and precision. This makes it possible to determine the potential use of the non-radioactive measurement method as an alternative to the radioactive method and thus lower the overall radioactive burden for patients and personnel.