What is the treatment for hyperthyroidism?

Treatment for Hyperthyroidism

For hyperthyroidism, you have three definitive treatment options: antithyroid drugs (methimazole preferred), radioactive iodine ablation, or surgery—with methimazole as first-line therapy for most patients, radioactive iodine as the most widely used treatment in the United States, and surgery reserved for specific indications. 1, 2

Initial Diagnostic Confirmation

Before initiating treatment, confirm the diagnosis biochemically:

• Check TSH with free T4 and/or free T3: Hyperthyroidism presents with suppressed TSH (<0.1 mIU/L) and elevated free T4 or free T3 1, 3
• Measure thyrotropin-receptor antibodies to identify Graves disease (the most common cause, affecting 2% of women and 0.5% of men) 3
• Obtain thyroid scintigraphy if thyroid nodules are present or the etiology remains unclear 3

First-Line Medical Management: Antithyroid Drugs

Drug Selection

Methimazole is the preferred first-line antithyroid drug due to superior efficacy and safety profile, except during the first trimester of pregnancy when propylthiouracil is preferred 1, 4. Propylthiouracil is otherwise reserved for patients intolerant to methimazole due to its potential to cause severe liver problems 1.

Dosing and Monitoring Strategy

• Target free T4 or free T3 in the high-normal range, not TSH normalization—TSH may remain suppressed for months even after achieving euthyroidism 1
• Monitor free T4 or free T3 every 2-4 weeks during initial treatment to guide dose adjustments 1
• Adjust methimazole based on free T4/T3 levels, not TSH—reducing dose based solely on suppressed TSH while free T4 remains elevated leads to inadequate treatment 1
• Continue treatment for 12-18 months in Graves disease to induce long-term remission (achievable in 20-50% of adults) 5, 6

Critical Adverse Effects Requiring Immediate Action

Monitor for these life-threatening complications:

• Agranulocytosis (typically within first 3 months): presents with sore throat and fever—requires immediate CBC and drug discontinuation 1
• Hepatotoxicity (especially with propylthiouracil): watch for fever, nausea, vomiting, right upper quadrant pain, dark urine, jaundice—discontinue immediately if suspected 1
• Vasculitis: monitor for skin changes, hematuria, or respiratory symptoms 1

Immediate Symptomatic Relief: Beta-Blockers

Start beta-blockers immediately for symptomatic control while awaiting thyroid hormone normalization:

• Atenolol 25-50 mg daily or propranolol provide rapid relief of tachycardia, tremor, and anxiety 1
• Target heart rate <90 bpm if blood pressure allows 1
• Reduce beta-blocker dose once euthyroid state is achieved to avoid bradycardia 1
• Beta-blockers are essential for rate control in hyperthyroid patients with atrial fibrillation (occurs in 5-15% of hyperthyroid patients, more frequently in those over 60 years) 1

Definitive Treatment Options

Radioactive Iodine (I-131) Ablation

Radioactive iodine is the most widely used treatment in the United States and is particularly preferred for:

• Elderly patients and those with heart disease—indicated immediately after reaching euthyroidism with antithyroid drugs 6, 2
• Toxic nodular goiter—radioiodine is the treatment of choice 5
• Patients who refuse or cannot tolerate antithyroid drugs 5

Absolute contraindications:

• Pregnancy and breastfeeding—pregnancy must be avoided for 4 months following administration 1
• Active Graves' ophthalmopathy—may worsen eye disease (corticosteroid cover may reduce this risk) 1, 5

The only long-term sequela is radioiodine-induced hypothyroidism, which is easily managed with levothyroxine replacement 5.

Surgical Thyroidectomy

Surgery (total or near-total thyroidectomy) is indicated for:

• Suspected or confirmed malignancy 6
• Large goiter (>80 grams) or goiter causing compressive symptoms (dysphagia, orthopnea, voice changes) 6, 3
• Pregnancy and breastfeeding (when radioiodine is contraindicated) 6
• Severe toxic side effects of antithyroid medications 6
• Requirement for immediate disease control 6
• Age younger than 5 years 6
• Active ophthalmopathy 6
• Patient preference for definitive treatment 6

Preoperative preparation: While achieving euthyroidism before surgery is ideal, recent evidence suggests thyroidectomy can be safely performed during the hyperthyroid phase by experienced teams without precipitating thyroid storm, provided the cardiovascular system is stabilized 7. However, combination therapy with thionamides, beta-blockers, and potentially iodine, corticosteroids, or other agents is recommended for optimal surgical conditions 7.

Special Populations

Subclinical Hyperthyroidism (Low TSH, Normal T3/T4)

Treat patients with TSH <0.1 mIU/L who are:

• Over 60 years old (3-fold increased risk of atrial fibrillation over 10 years) 1
• At increased risk for heart disease, osteopenia, or osteoporosis 1
• Estrogen-deficient women (due to bone loss risk) 1

Do not routinely treat patients with TSH 0.1-0.45 mIU/L due to insufficient evidence of adverse outcomes, unless elderly with cardiovascular risk factors 1.

Pregnancy

• First trimester: Use propylthiouracil (methimazole is teratogenic) 1
• After first trimester: Switch to methimazole 1
• Goal: Maintain free T4 or free T3 in high-normal range using lowest possible dose 1
• Both drugs are compatible with breastfeeding 1

Destructive Thyroiditis

This is self-limited and requires different management:

• Beta-blockers for symptomatic relief only—no antithyroid drugs indicated 1
• Monitor with symptom evaluation and free T4 testing every 2 weeks 1
• Introduce levothyroxine if patient becomes hypothyroid (low free T4/T3, even if TSH not yet elevated) 1

Critical Pitfalls to Avoid

• Never reduce methimazole based solely on suppressed TSH while free T4 remains elevated—this leads to treatment failure 1
• Never attempt cardioversion in thyrotoxic patients without first achieving euthyroid state—antiarrhythmic drugs and cardioversion are unsuccessful while thyrotoxicosis persists 1
• Never use radioiodine in pregnancy or breastfeeding—absolute contraindication 1
• Never delay treatment in patients over 60 years with TSH <0.1 mIU/L—they face 3-fold increased cardiovascular mortality 1