RT Book, Section A1 Weiss, Roy E. A1 Refetoff, Samuel A2 Hall, Jesse B. A2 Schmidt, Gregory A. A2 Kress, John P. SR Print(0) ID 1107711545 T1 Thyroid Disease T2 Principles of Critical Care, 4e YR 2015 FD 2015 PB McGraw-Hill Education PP New York, NY SN 9780071738811 LK accessmedicine.mhmedical.com/content.aspx?aid=1107711545 RD 2024/03/28 AB Virtually all patients admitted to an ICU have low levels of serum triiodothyronine (T3), and 30% to 50% have low levels of thyroxine (T4) with normal or low levels of serum thyrotropin (TSH).Patients who have a T4 level of less than 3.0µg/dL despite normal levels of T4-binding proteins have a 68% to 84% mortality rate.T3 is the logical choice for critically ill patients requiring thyroid hormone replacement.Early intubation and mechanical ventilation are crucial for successful treatment of myxedema coma.Management of myxedema coma should include administration of glucocorticoids while the adrenal status is being assessed.Alterations in thyroid function change the metabolism of almost all drugs, and the doses need careful adjustment to prevent drug toxicity or decreased efficacy.Autonomous hypersecretion and exogenous overdose of thyroid hormone are the most common causes of severe thyrotoxicosis.Hyperpyrexia and altered mental status are the hallmarks of thyroid storm.Medical treatment of severe hyperthyroidism usually normalizes circulating thyroid hormone levels in 2 to 3 weeks, except under circumstances of iodine overload, in which case hyperthyroxinemia may persist for months.Blockade of hormonal secretion is best accomplished by the addition of stable iodine to an antithyroid drug regimen.In severe thyrotoxicosis, treatment with iopanoic acid can be lifesaving.β-Blockers prevent thyroid storm in the thyrotoxic patient undergoing surgery, and they may ameliorate cardiovascular dysfunction in thyroid storm, but their side effects often interfere with therapy in the elderly, in patients with asthma, and in patients with cardiomyopathy.Amiodarone-induced thyrotoxicosis in a critically ill patient should be managed with methimazole (30-50 mg/d), potassium perchlorate (500 mg twice a day), and prednisone (30-40 mg/d).After gastric aspiration and lavage, only symptomatic and supportive treatment is needed in cases of levothyroxine overdose.Neonatal thyrotoxicosis can be life threatening; it is usually caused by transplacental transfer of thyroid-stimulating antibodies. It is transient and requires only short-term treatment.