MCQ – 120443

The ideal substance for measuring GFR should have all of the following characteristics except?

A.	Should be secreted in tubules
B.	It should be non-toxic
C.	Should not remain in the body
D.	Should not be protein bound

Show Answer

Correct Answer � A Explanation

The correct answer is:

a. Should be secreted in tubules

Explanation:

Option A is incorrect because substances used to measure GFR should not be secreted in the renal tubules. If a substance is secreted in the tubules, it will not accurately reflect the filtration rate because it would increase the total amount excreted, making it appear as if the GFR is higher than it actually is. The ideal substance for measuring GFR should be filtered at the glomerulus but should not be reabsorbed or secreted by the tubules, ensuring an accurate estimation of the renal filtration rate.

Incorrect Options: 

Option B. It should be non-toxic: The substance used to measure GFR should be non-toxic to ensure the safety of the patient undergoing the test.

Option C. Should not remain in the body: The substance should be freely filtered by the glomerulus and should not be reabsorbed or secreted by the renal tubules. Substances that are neither reabsorbed nor secreted provide an accurate estimation of GFR because they are entirely excreted in the urine and do not remain in the body.

Option D. Should not be protein bound: Protein-bound substances are generally not freely filtered by the glomerulus because they are too large to pass through the filtration membrane. The ideal substance for measuring GFR should be freely filtered, meaning it can easily pass through the glomerular filtration barrier.