A client on a loop diuretic (furosemide) reports muscle cramps and fatigue. Blood work shows potassium 3.1 mEq/L. Which intervention should the nurse prioritize?

HYPOKALEMIA from loop diuretics: NORMAL POTASSIUM: 3.5-5.0 mEq/L; MILD HYPOKALEMIA: 3.0-3.4 mEq/L (client's 3.1 mEq/L is mild); SYMPTOMS: Muscle weakness, cramps, fatigue (matching this client's complaints); SEVERE (<3.0): Potentially fatal cardiac dysrhythmias (PVCs, ventricular fibrillation), severe weakness; ECG CHANGES: Flattened T waves, U waves, prolonged QU interval; INTERVENTION SEQUENCE: Notify provider with lab value and symptoms; HOLD furosemide (adding more diuretic increases potassium loss); REPLACE potassium: Oral KCl preferred when tolerated (less dangerous than IV); IV KCl if severe or oral not possible (NEVER IV push — causes cardiac arrest); DIETARY: Bananas, oranges, melons, potatoes, leafy greens, yogurt; MONITORING: Repeat labs after replacement; cardiac monitoring if K+ <3.0; assess muscle weakness and ECG; RENAL: Ensure adequate renal function before aggressive replacement — hyperkalemia is also dangerous.