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
A) secreted and reabsorbed by the tubules.
B) neither reabsorbed nor secreted by the tubules.
C) secreted by the tubules.
D) reabsorbed by the tubules.
E) none of these answers.

Question

Quizplus · Accepted Answer

If a substance is neither reabsorbed nor secreted by the tubules, then its plasma clearance will be equal to the GFR. This is because the only way for the substance to leave the plasma is through the glomerulus, and if it is not reabsorbed or secreted by the tubules, then it must be excreted in the urine at the same rate as it is filtered at the glomerulus. Examples of substances that meet these criteria include inulin and creatinine.

The Plasma Clearance of a Substance Can Be Used to Calculate