A nurse is caring for a client who is postoperative and has an NG tube that has drained 2,500 mL in the past 6 hr. The nurse should monitor the client for which of the following electrolyte imbalances?

A. Calcium levels are not typically affected by NG tube drainage. B. Large-volume NG tube drainage results in loss of gastric secretions, which are rich in potassium, placing the client at risk for hypokalemia. C. Magnesium levels are not commonly affected by gastric fluid loss. D. Hemoglobin is not directly affected by NG tube drainage unless significant blood loss occurs.