This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Excretory System (Kidney, Bladder) Acid-Base Balance, Subject name: Physiology
[{'content': 'Ideal substance for measuring GFR should have all characteristics except \nSelect and explain. \nA. Should be secreted in tubules, B. Should be non-toxic, C. Should not remain in the body, D. Should not be protein bound', 'role': 'user'}, {'content': 'Answer: A \nExplanation: The Ideal substance to measure GFR is Inulin or following reasons ; It is non-toxic; It is freely filterable by the glomeruli; it is not bound to proteins It is neither secreted nor reabsorbed by the tubules; It is not synthesized, stored, or destroyed by the kidney . Thus, Filtered inulin = excreted inulin .Hence, it will give an exact estimate of the GFR. Endogenous creatinine clearance is used most commonly used to estimate the GFR.', 'role': 'assistant'}]