The purpose of the study is to validate a new reference marker for evaluation of renal function (glomerular filtration rate).

Chronic kidney disease (CKD) is a worldwide public health problem with an increasing incidence and prevalence, poor outcomes (kidney failure, complications of decreased kidney function and cardiovascular disease), and high cost. Some of the adverse outcomes can be prevented or delayed by early detection and treatment. However, CKD is frequently underdiagnosed and undertreated. The glomerular filtration rate (GFR) is considered as the best index of renal function. The clinical action plan promoted by International Guidelines groups refers to GFR values. Despite recent improvements, prediction equations developed in order to estimate GFR elicit a huge lack of accuracy when considering the individual patient, especially in case of early CKD. Rigorous assessment of GFR requires the measurement of urinary or plasma clearance of an ideal exogenous filtration marker which is either non-radioactive (inulin, iothalamate, or iohexol) or radioactive ( 51Cr-EDTA or 99mTc DTPA. Measuring clearance with the use of exogenous markers is difficult to perform in clinical practice because it is expensive and cumbersome and needs specialised laboratories and thus, is underused. There is an unmet need for the development of a new non-radioactive GFR tracer that could combine both the analytical accuracy of radioactive tracers and the simplicity of its measurement. Such a tracer should improve clinical care and follow-up of patients.