Question

Which among the following is true regarding creatinine clearance?

• A. Equal to inulin clearance
• B. It is less than inulin clearance
• C. It is more than inulin clearance
• D. Equal to renal plasma flow

Hint:

While creatinine clearance is often used to estimate GFR, it is important to note that it also includes some secretion, making it a slight overestimate of GFR.

Answer 1

The Correct Option is A

Creatinine clearance is often used as an estimate for glomerular filtration rate (GFR) since creatinine is freely filtered by the kidneys and is neither reabsorbed nor secreted to a significant extent. Inulin clearance is considered the gold standard for measuring GFR, as inulin is neither reabsorbed nor secreted by the kidneys. However, when it comes to the relationship between creatinine clearance and renal plasma flow (RPF), creatinine clearance is roughly equal to renal plasma flow. This is because a portion of creatinine is secreted into the urine in addition to being filtered, making its clearance close to RPF. Thus, the correct answer is Equal to renal plasma flow (Option 4). While inulin clearance exactly measures GFR, creatinine clearance tends to overestimate GFR due to some secretion of creatinine by the renal tubules.