The nurse is preparing to assist with blood collection on a newly admitted patient who has been taking phenytoin for several years.The provider has ordered a complete blood count and liver function tests.Which other blood test will the nurse discuss with the provider?

Choice A rationaleCoagulation studies assess the blood's ability to clot and are not directly related to the monitoring of phenytoin therapy. These tests are more relevant for patients with bleeding disorders or those on anticoagulant therapy.Choice B rationaleSerum electrolytes, including levels of sodium, potassium, and calcium, are important for overall health but are not specifically indicative of phenytoin levels. Phenytoin may affect calcium metabolism, but it is not the primary focus for routine monitoring.Choice C rationaleRenal function tests are crucial for assessing kidney function but do not directly monitor phenytoin therapy. Phenytoin is primarily metabolized in the liver, making liver function tests more relevant.Choice D rationaleBlood glucose levels should be monitored in patients taking phenytoin as the drug can cause alterations in blood glucose levels. Both hypoglycemia and hyperglycemia have been reported, so it is important to check glucose levels to ensure they remain within a normal range.