Given the following data for substance X (GFR = 125 ml/min, Tm = 125 mg/min, at a plasma concentration of 200 mg/100 ml), how much of substance X is filtered, reabsorbed, and excreted?
A)200 mg/min filtered, 125 mg/min reabsorbed, 75 mg/min excreted
B)250 mg/min filtered, 125 mg/min reabsorbed, 125 mg/min excreted
C)125 mg/min filtered, 125 mg/min reabsorbed, 0 mg/min excreted
D)250 mg/min filtered, 200 mg/min reabsorbed, 50 mg/min excreted
E)none of these

Question

Quizplus · Accepted Answer

The filtered load is calculated as GFR (125 ml/min) x plasma concentration (200 mg/100 ml = 2 mg/ml) = 250 mg/min. The maximum reabsorption (Tm) is 125 mg/min, so 125 mg/min is reabsorbed. The excreted amount is the filtered load minus the reabsorbed amount: 250 mg/min - 125 mg/min = 125 mg/min.

Given the Following Data for Substance X (GFR = 125