The agitated client is hospitalized with tachycardia, dyspnea, and intermittent chest palpitations. The client's BP is 170/110 mm Hg, and HR is 130 bpm. The client's health history reveals thinning hair, recent 10-lb weight loss, increased appetite, fine hand and tongue tremors, hyperreflexic tendon reflexes, and smooth, moist skin. Which prescribed intervention should be the nurse's priority?

D Propylthiouracil 600-mg oral loading dose; then 200 mg orally q4h. B Obtain thyroid-stimulating hormone (TSH) and free T4 levels. C Propranolol 2 mg IV q15 min or until symptoms are controlled. A 12-lead electrocardiogram (ECG) and cardiac enzyme levels.