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Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
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Ideal substance for measuring GFR should have the following characteristics EXCEPT:
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The correct answer is  Ans. a (Should be secreted in tubules). (Ref. Ganong, Physiology, 21st/pg.709)GLOMERULAR FILTRATION RATE (GFR)Characteristics of a substance suitable for measuring the GFR, by determining its clearance:1. Freely filtered (i.e., not bound to protein in plasma or sieved in the process of ultrafiltration).2. Not reabsorbed or secreted by tubules.3. Not metabolized.4. Not stored in kidneys.5. Not toxic.6. No effect on filtration rate.7. Preferably easy to measure in plasma and urine.Inulin is freely filtered and is neither reabsorbed nor secreted.GFR by definition is net volume of plasma from which a substance is cleared completely per unit time.GFR =UVPWhere U -- concentration in urineV -- volume of urine passed/minuteP -- concentration in plasma.Clinically, creatinine clearance is good measure of GFR.