Final answer:
Option (A), A potassium level measurement is commonly performed for patients taking furosemide (Lasix) to monitor for potential hypokalemia due to the diuretic effect of the medication.
Step-by-step explanation:
A laboratory test commonly performed on a patient taking furosemide (Lasix) is a potassium level measurement. Furosemide is a loop diuretic that can cause the kidneys to excrete more sodium, water, and potassium, potentially leading to hypokalemia (low potassium levels).
Monitoring potassium levels is critical for patients on furosemide to prevent complications associated with electrolyte imbalance. This is consistent with clinical practices where sodium, potassium, and chloride are typically analyzed in a routine urine sample to reflect the rates of excretion of these ions and maintain proper kidney function.