<prompt> Substance ideal for GFR estimation is?Inulin clearancePAH clearanceUrea clearanceAll of the above  <response>: Ans: a Inulin clearance: Ganong, 22nd ed,p. 706GFR can be measured in intact experimental animals and humans by measuring the excretion and plasma level of a substance that is freely filtered through the glomeruli and neither secreted nor reabsorbed in the tubules.Inulin is a polymer of fructose with a molecular weight of 5200 obtained from Dahlia tubers, meets the above criterion and is extensively used to measure GFR.Remember Ideal substance to measure GFR-InulinSubstance used for practical purposes-CreatinineSubstance used to measure renal blood flow-PAHNormal GFR of human beings-125 mlmin ClearanceCxUVPUrine concentrationsne flowtime VPlasma concentration. 