A nurse is caring for a client receiving febuxostat for long-term treatment of gout. Which of the following adverse effects should the nurse closely monitor for?

A. Hypertension is not a direct adverse effect of febuxostat; monitoring blood pressure is important but not the primary concern with this medication. B. Malignant hyperthermia is a rare condition typically associated with certain anesthetic agents and is not related to febuxostat. C. Steven's Johnson Syndrome is a serious skin reaction that can occur with some medications, but it is not specifically associated with febuxostat. D. Renal impairment is a known risk with febuxostat, and the nurse should monitor renal function closely, as gout can also be exacerbated by kidney issues and febuxostat is primarily excreted by the kidneys.