Hyperthyroidism Quiz: Ace Your Exams

A 47-year-old woman presents to the emergency department due to altered mental status. She is accompanied by her partner, who reports that the patient was in her usual state before having severe nausea and vomiting during dinner. Medical history is remarkable for long-standing Graves disease, but the patient has been non-compliant with medications. Last week, she had an upper respiratory infection that was resolved without treatment. Temperature is 40°C (104.0°F), pulse is 155/min and irregular, and blood pressure is 155/100 mmHg. On physical examination, the patient is agitated and in severe distress. The patient’s skin is moist, and a large goiter is noted. Laboratory tests show an elevated T3 and T4, low TSH, elevated liver enzymes, mild hyperglycemia, and leukocytosis. The patient is administered IV propranolol, propylthiouracil, and hydrocortisone. An hour later, the doctor adds a potassium iodide-iodine (Lugol's) solution to the treatment. This medication has which of the following immediate effects?