Management of Hyperthyroidism and Thyroid Storm
Primary Treatment Goal: Restore Euthyroid State
The cornerstone of managing hyperthyroidism is restoring a euthyroid state, which often leads to spontaneous resolution of complications including atrial fibrillation. 1
Acute Management Algorithm
Rate Control (First-Line Intervention)
β-blockers are the recommended first-line agents for controlling ventricular rate and managing cardiovascular symptoms 1
When β-blockers are contraindicated, non-dihydropyridine calcium channel antagonists (diltiazem or verapamil) are the recommended alternatives 1
Antithyroid Medications
Initiate methimazole at 5-15 mg daily (or propylthiouracil as alternative) to block thyroid hormone synthesis 2, 3
- Monitor free T4 or free thyroxine index every 2-4 weeks during titration, targeting high-normal range with the lowest effective dose 2
- Propylthiouracil has the additional benefit of inhibiting peripheral conversion of T4 to T3, which may be advantageous in thyroid storm 3
- Recent evidence shows no significant mortality difference between propylthiouracil and methimazole in thyroid storm (8.5% vs 6.3%, adjusted risk difference 0.6%, P=.64), suggesting current guideline preferences for propylthiouracil may warrant reevaluation 4
Critical Safety Monitoring
Patients must immediately report sore throat, fever, skin eruptions, headache, or general malaise, as these indicate potential agranulocytosis requiring immediate drug discontinuation and complete blood count evaluation 2
Cardiovascular Complications
Atrial Fibrillation Management
- Antithrombotic therapy is recommended based on CHA2DS2-VASc stroke risk factors, not thyroid status alone 1
- Cardioversion should be deferred until euthyroid state is achieved, as antiarrhythmic drugs and direct-current cardioversion are generally unsuccessful while thyrotoxicosis persists 1
- Once euthyroid, anticoagulation recommendations follow standard guidelines for patients without hyperthyroidism 1
Thyroid Storm Specific Management
Thyroid storm is a life-threatening emergency with mortality rates up to 30% if untreated, requiring aggressive multimodal therapy 5, 6, 7
Treatment Components:
- High-dose intravenous β-blockers (propranolol preferred) 1
- Antithyroid medications (methimazole or propylthiouracil) 2, 3, 4
- Corticosteroids to block peripheral T4 to T3 conversion 8
- Supportive care addressing hyperthermia, tachycardia, respiratory distress, gastrointestinal symptoms, and altered mental status 8, 7
Refractory Cases:
Therapeutic plasma exchange is a safe and effective option when conventional treatments fail or are not tolerated 5
- Removes T3, T4, autoantibodies, catecholamines, and cytokines 5
- Typically performed daily for 4 days with 1.0 plasma volume exchange 5
- Can normalize thyroid hormones and resolve symptoms when pharmacotherapy is unsuccessful 5
Important Clinical Pitfalls
- Avoid iodinated contrast in patients with known or suspected hyperthyroidism, as CT contrast exposes patients to 14-35 million mcg of iodine versus the recommended 150 mcg daily intake, potentially precipitating thyroid storm (Jod-Basedow phenomenon) 8
- Amiodarone must be discontinued if hyperthyroidism develops during treatment 1
- Digoxin is less effective for rate control when adrenergic tone is high, making it a poor choice in acute thyrotoxicosis 1
Definitive Treatment Planning
- Surgery (total thyroidectomy) should be considered for patients with concurrent cancer, pregnancy, compressive symptoms, or Graves' disease with ophthalmopathy 6
- Patients must achieve euthyroid state preoperatively with antithyroid medications and be on β-blockers for cardiovascular manifestations 6
- Radioactive iodine is contraindicated in Graves' disease with ophthalmic manifestations 6