<prompt> Which of the following Ideal substance used to measure GFRInulinCreatinineUreaAll of the above  <response>: Inulin 265-66-K.S 3rd 706,7J2-GN 645- Ganong 23rd1 Measurement of GFR - A substance that is completely filtered but neither reabsorbed nor secreted should be used to measure GFR. Inulin is a substance that is completely filtered, but it is neither reabsorbed nor secreted. So Inulin is the ideal substance used to measure GFR. Creatinine clearance is also used to measure GFR, are inaccurate at low creatinine levels. Endogenous creatinine clearance is a worthwhile index of renal functions2 Measurement of Renal plasma flow. To measure renal plasma flow, a substance, which is filtered and secreted but not reabsorbed should be used. Such a substance is Para-aminohippuric acid PAH. PAH clearance indicates the amount of plasma passed through kidneys. Diodrast clearance also can be used to measure renal plasma flow.3 Measurement of Renal blood flow. Two factors1. Renal plasma flow - PAH clearance2. Percentage of plasma volume in the bloodRenal blood flow Renal plasma flow of plasma in blood 