The healthcare provider prescribes lithium carbonate for a client diagnosed with bipolar, manic depression. It is most important for the nurse to review which laboratory finding prior to beginning the drug therapy?

A) Alkaline phosphatase levels are not typically monitored specifically for lithium therapy. B) Blood glucose levels may be monitored periodically during lithium therapy, but serum creatinine levels are more crucial for assessing renal function, as lithium is excreted primarily by the kidneys. C) White blood count may be monitored for signs of infection but is not directly related to lithium therapy. D) Serum creatinine levels should be monitored before initiating lithium therapy and periodically thereafter due to the risk of lithium-induced nephrotoxicity.