The nurse caring for a client with a serum calcium of 6.8 mg/dL. What would the nurse expect the change on the electrocardiogram (ECG)?

Prolonged QT interval.

The normal serum calcium level is 8.6 to 10 mg/dL. A serum calcium level lower than 8.6 mg/dL indicates hypocalcemia. Electrocardiographic changes that occur in a client with hypocalcemia include a prolonged ST or QT interval.Options C and D: A shortened ST segment and a widened T wave occur with hypercalcemia.