This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Pharmacokinetics, Subject name: Pharmacology
Renal threshold of drug means - 
Select and explain. 
A. Drug concentration above which it appears in urine, B. Drug concentration below which it appears in urine, C. Drug concentration above which it appears in blood, D. Drug concentration below which it appears in urine
A: Drug concentration above which it appears in urine
Answer: A: Drug concentration above which it appears in urine 
Explanation: Ans. is 'a' i.e., Drug concentration above which it appears in urine Renal Thresholdo The renal threshold is the concentration of a substance dissolved in the blood above which the kidneys begin to remove it into the urine. When the renal threshold of a substance is exceeded, reabsorption of the substance by the proximal convoluted tubule is incomplete; consequently, part of the substance remains in the urine,o Thus renal threshold is the Drug concentration above which it appears in urine.