Which Laboratory Result for a Patient Whose Cardiac Monitor Shows

Which laboratory result for a patient whose cardiac monitor shows multifocal premature ventricular contractions (PVCs) is most important for the nurse to communicate to the health care provider?

A) Blood glucose 228 mg/dL
B) Serum chloride 90 mEq/L
C) Serum sodium 133 mEq/L
D) Serum potassium 2.8 mEq/L