Final answer:
The nurse should question the prescription to administer IV chlorothiazide based on the laboratory values of serum sodium and serum potassium.
Step-by-step explanation:
The nurse should question the prescription to administer IV chlorothiazide based on the laboratory value of serum sodium = 128 mEq/L (128.0 mmol/L) and serum potassium = 5.3 mEq/L (5.3 mmol/L).
In heart failure, it is important to monitor the electrolyte levels, especially serum sodium and potassium, as they can be indicative of fluid and electrolyte imbalance. A low serum sodium level (hyponatremia) and a high serum potassium level (hyperkalemia) can occur in heart failure and may worsen with the administration of chlorothiazide, a diuretic that can further decrease sodium and increase potassium levels.