This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Medicine
[{'content': 'The nurse is assigned to care for a client with cytomegalovirus retinitis and acquired immunodeficiency syndrome who is receiving foscarnet (Foscavir). The nurse carefully monitors which of the following laboratory test during the treatment with this medication, except? \nSelect and explain. \nA. Serum creatinine., B. Serum calcium., C. Serum magnesium., D. Serum sodium.', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Renal impairment is the major toxicity involve in\xa0Foscarnet\xa0(Foscavir); This medicine also may cause decreased levels of\xa0calcium,\xa0magnesium, phosphorous, and\xa0potassium.', 'role': 'assistant'}]