This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Renal physiology, Subject name: Physiology
What is implied if a drug has more clearance than the GFR? 
Select and explain. 
A. Drug is reabsorbed in the tubules, B. Drug is secreted in the tubules, C. Drug is excreted in bile, D. Drug is neither secreted nor reabsorbed
B: Drug is secreted in the tubules
Answer: B: Drug is secreted in the tubules 
Explanation: The clearance of the substance equals the GFR if there is no net tubular secretion or reabsorption (Inulin), exceeds the GFR if there is net tubular secretion (PAH), and is less than the GFR if there is net tubular reabsorption (Glucose). Ref: Ganong 25th ed/page 679