You Need to Evaluate Kidney Function in a 55-Year?-Old Obese

You need to evaluate kidney function in a 55-year?-old obese man with type 2 diabetes; you ask him to collect his urine over a 24-hour period. He collects 4,320 mL of urine. The clinical laboratory returns the following results from analysis of his urine and plasma samples: · Plasma creatinine = 3.0 mg/100 mL
· Urine creatinine = 40 mg/100 mL
· Plasma potassium = 5.0 mmol/L
· Urine potassium = 20 mmol/L

What is his approximate GFR, assuming that he collected all of his urine in the 24-hour period?

A) 10 mL/min
B) 20 mL/min
C) 30 mL/min
D) 40 mL/min
E) 80 mL/min