DYNAMic Renal Assessment: NOvel Methods to Assess KIDNEY Functional Reserve

This study is testing new ways to measure how well the kidneys can handle extra work — called kidney functional reserve. It focuses on people with sickle cell disease who have kidney involvement, as well as people who have previously donated a kidney. **You may be eligible if...** - You have sickle cell disease with kidney involvement (sickle cell nephropathy) - OR you have previously donated a kidney as a living donor - You are 40 years of age or older - You have no known allergies to the medications used in the study - You are able to give written informed consent **You may NOT be eligible if...** - You are under 40 years old - You are pregnant or breastfeeding - You are currently enrolled in another interventional study - You are unable or unwilling to provide consent Talk to your doctor to see if this trial is right for you.