A client is admitted with bipolar disorder and lithium carbonate is prescribed. Before administering the daily dose, the practical nurse (PN) plans to monitor the client's serum lithium levels. Which physiologic action necessitates frequent monitoring of serum lithium levels?

D Serum levels reflect client compliance and support behavior changes. C Foods containing tyramine influence the drug's metabolism. B Sodium influences a narrow margin between therapeutic and toxic levels. A Myelosuppression and agranulocytosis are common side effects.