Final answer:
The nurse should monitor ionized calcium levels in a patient admitted with tetany because decreased ionized calcium causes tetany.
Step-by-step explanation:
When a patient is admitted with tetany, it's important to monitor the levels of ionized calcium in the blood. Tetany can be caused by decreased levels of ionized calcium, which can occur due to a variety of factors including an increase in blood pH, poor absorption from the intestine, decreased dietary intake, or increased renal excretion as in nephritis or parathyroid deficiency. Therefore, the nurse should plan to monitor the patient's ionized calcium levels to address and manage their condition effectively.