Used as a diagnostic agent to measure renal plasma flow and kidney function. It is particularly effective in assessing effective renal plasma flow (ERPF) due to its high extraction rate by the renal tubules. Administered intravenously, it helps determine glomerular filtration rate (GFR) in clinical and research settings. Also employed in studies involving drug interactions and transport mechanisms in the kidneys. Its ability to be actively secreted by the proximal tubules makes it a standard reference compound in nephrology research.