Thyrotoxic Storm

Abstract

Thyrotoxic storm is a syndrome of exaggerated thyrotoxicosis with systemic decompensation seen in 1-2% of hospital admissions for thyrotoxicosis. The diagnosis is based on recognition of typical cardinal manifestations, but even when diagnosed and treated, mortality rates are high. Results of thyroid function tests may be no more abnormal than those seen in uncomplicated thyrotoxicosis. Often, there is a history of partially treated thyrotoxicosis, and/or decompensation related to a precipitating event such as infection, stroke, pulmonary embolism, or radioiodine therapy. Treatment must be aggressive and includes volume repletion with i.v. glucose and saline, and pressor agents may be needed. Patients belong in an intensive care unit, with a cooling blanket for hyperpyrexia. Appropriate cardiac medications are employed to control ventricular rate in those with atrial fibrillation. The thyroid is blocked by large doses of antithyroid agent. In patients unable to swallow, tablets can be crushed and given by nasogastric tube or per rectum. After antithyroid drugs are started, stable iodine as Lugol's solution is given to block further hormone release from the gland. Sodium ipodate can be used instead of iodine and has the advantage of inhibiting conversion of T4 to T3. In severe cases, thyroid hormone may be removed from the circulation by peritoneal dialysis or plasmapheresis, and cholestyramine resin may be used to bind T4 and T3 within the gastrointestinal tract. β-adrenergic antagonists such as propranolol are given, or the very short-acting β-adrenergic blocker, esmolol, has also been used with success. A Swan-Ganz catheter is used to monitor central hemodynamics, especially in patients receiving high-dose propranolol, pressors, digoxin, diuretics, and fluids. Large doses of dexamethasone have been given based on presumed increased glucocorticoid requirements in thyrotoxicosis and because adrenal reserve may be reduced. Therapy must be continued until a normal metabolic state is achieved, at which time iodine is progressively withdrawn and plans made for definitive treatment.