Explanation:

When a patient is receiving a high dose of intravenous azithromycin, which is a macrolide antibiotic, in combination with acetaminophen, a potentially hepatotoxic drug, the nurse should monitor liver enzymes. High doses of macrolides when taken with hepatotoxic drugs like acetaminophen can lead to hepatotoxicity. Reviewing liver enzymes helps in early detection of liver damage. Complete blood counts (Choice A) are not typically affected by azithromycin or acetaminophen. Electrolytes (Choice B) are not directly impacted by these medications. Urinalysis (Choice D) is not specifically indicated for monitoring the side effects of azithromycin and acetaminophen combination therapy.