Correct Answer: B

Rationale: The correct statement to include when teaching a client about Diltiazem is to avoid drinking grapefruit juice. Grapefruit juice can increase the levels of diltiazem in the blood, leading to potential toxicity and increased side effects. It is important for the client to be aware of this interaction to ensure the safe and effective use of the medication. Option A is incorrect because dry mouth is not a common side effect of Diltiazem. Option C is incorrect because Diltiazem is actually used to treat rapid heart rates. Option D is unrelated to the medication and not relevant to the teaching.

Correct Answer: A

Rationale: The correct answer is to check the thyroid hormone assay. Long-term lithium use can result in thyroid dysfunction, making it crucial to monitor the client's thyroid function regularly to detect any abnormalities early and prevent potential complications. Liver function tests (choice B) are not specifically associated with lithium therapy. Erythrocyte sedimentation rate (choice C) is a nonspecific test for inflammation and not directly related to lithium therapy. Brain natriuretic peptide (choice D) is a test used to diagnose heart failure and is not relevant to monitoring lithium therapy.

Correct Answer: A

Rationale: The nurse should monitor the client's potassium levels when taking Furosemide because the medication can lead to hypokalemia. Hypokalemia is a potential side effect of Furosemide, a loop diuretic, due to increased potassium excretion in the urine. Monitoring potassium levels is crucial to prevent complications such as cardiac dysrhythmias associated with low potassium levels. Therefore, choices B (Sodium level), C (Hemoglobin A1C), and D (BUN) are incorrect as they are not directly influenced by Furosemide therapy for heart failure.

Correct Answer: D

Rationale: When administering Phenytoin, monitoring the patient's behavior is important to assess for any changes that may indicate adverse effects. Monitoring therapeutic blood levels helps ensure the medication is within the effective range and not causing toxicity. Additionally, being vigilant for signs of Stevens-Johnson syndrome, a severe skin reaction associated with Phenytoin use, is crucial for early detection and intervention. Therefore, monitoring behavior, therapeutic blood levels, and for signs of Stevens-Johnson syndrome are all essential when administering Phenytoin.

Correct Answer: D

Rationale: Metformin is excreted by the kidneys, and impaired kidney function can lead to an increased risk of lactic acidosis, a serious side effect. Therefore, it is important to monitor kidney function regularly while a client is on Metformin. Hemoglobin A1C is used to monitor long-term glucose control, but kidney function is the priority for monitoring Metformin therapy.