MCAT Question A Day - 7/29/14 - Answer!
Tests reveal the presence of glucose in a patient's urine. This is an indication that:
A. glucose transporters in the loop of Henle are not functioning properly.
B. the patient is healthy. as glucose normally appears in the urine.
C. the proximal tubule is over-secreting glucose.
D. glucose influx into the filtrate is occurring faster than it can be reabsorbed.
D is correct. Glucose is normally completely reabsorbed from the filtrate and thus does not appear in the urine. When glucose does appear in the urine, the glucose transporters in the PCT (not in the loop of Henle, as stated in answer choice A) are unable to reabsorb all of the glucose from the filtrate. C is wrong because the proximal tubule does not secrete glucose.
D is correct. Glucose is normally completely reabsorbed from the filtrate and thus does not appear in the urine. When glucose does appear in the urine, the glucose transporters in the PCT (not in the loop of Henle, as stated in answer choice A) are unable to reabsorb all of the glucose from the filtrate. C is wrong because the proximal tubule does not secrete glucose.
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