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 the net renal tubular secretion rate of potassium in the patient described in question?

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 the net renal tubular secretion rate of potassium in the patient described in question?