The plasma clearance of a substance can be used to calculate the glomerular filtration rate (GFR) if that substance is freely filtered at the glomerulus and is
A)secreted and reabsorbed by the tubules.
B)neither reabsorbed nor secreted by the tubules.
C)secreted by the tubules but not reabsorbed by the tubules.
D)reabsorbed by the tubules but not secreted by the tubules.

Question

Quizplus · Accepted Answer

In order to calculate GFR, we need a substance that is freely filtered at the glomerulus and is neither reabsorbed nor secreted by the tubules. This is because the amount of the substance that appears in the urine is equal to the amount that is filtered, so if any is reabsorbed or secreted, it would not accurately reflect GFR. One example of such a substance is inulin, although creatinine is commonly used in clinical practice as a close approximation.

The Plasma Clearance of a Substance Can Be Used to Calculate