What is the recommended management for a patient with hyperthyroidism?

Hyperthyroidism Management

First-Line Medical Therapy

Methimazole is the preferred first-line antithyroid drug for hyperthyroidism due to superior efficacy and safety profile, except during the first trimester of pregnancy when propylthiouracil is preferred. 1

Initial Treatment Approach

• Start methimazole 10-30 mg once daily as the primary antithyroid drug for most patients with hyperthyroidism 1, 2
• Add beta-blockers immediately (atenolol 25-50 mg daily or propranolol) for symptomatic relief of tachycardia, tremor, and anxiety while awaiting thyroid hormone normalization 1, 3
• Target heart rate <90 bpm if blood pressure allows when titrating beta-blocker dose 1

Monitoring Strategy

• Monitor free T4 or free T3 index every 2-4 weeks during initial treatment to maintain levels in the high-normal range using the lowest effective dose 1
• Do NOT target TSH normalization initially, as TSH may remain suppressed for months even after achieving euthyroidism 1
• Adjust methimazole based on free T4/T3 levels, not TSH - if free T4/T3 drops below normal, reduce or temporarily discontinue methimazole 1

Critical Safety Monitoring

Agranulocytosis (Most Dangerous Complication)

• Occurs within the first 3 months of thioamide therapy 1
• Presents with sore throat and fever - requires immediate CBC and drug discontinuation 1
• Starting dose should not exceed 15-20 mg/day methimazole to reduce dose-dependent agranulocytosis risk 4
• Instruct patients to report immediately: sore throat, skin eruptions, fever, headache, or general malaise 5, 6

Hepatotoxicity (Especially with Propylthiouracil)

• Monitor for fever, nausea, vomiting, right upper quadrant pain, dark urine, and jaundice 1
• Discontinue drug immediately if suspected 1
• Propylthiouracil can cause severe liver failure requiring transplantation or resulting in death, particularly in pediatric patients 6, 4

Vasculitis

• Can be life-threatening - watch for skin changes, hematuria, or respiratory symptoms 1
• Promptly report new rash, decreased urine output, dyspnea, or hemoptysis 5, 6

Pregnancy Considerations

Propylthiouracil is the preferred agent during the first trimester due to methimazole's association with congenital malformations (aplasia cutis, choanal/esophageal atresia) 1, 5, 2

• Switch to methimazole after the first trimester to reduce maternal hepatotoxicity risk 1, 6
• Maintain free T4 or free T3 index in the high-normal range using the lowest possible thioamide dosage 1
• Both drugs are compatible with breastfeeding 1, 6, 2

Definitive Treatment Options

Radioactive Iodine (I-131)

• Growing as first-line therapy for hyperthyroidism, particularly for toxic nodular goiter 7
• Absolutely contraindicated in pregnancy and breastfeeding 1
• Avoid pregnancy for 4 months following administration 1, 7
• May worsen Graves' ophthalmopathy - consider corticosteroid cover to reduce this risk 1, 7
• Stop antithyroid drugs at least one week prior to radioiodine to reduce treatment failure risk 4

Surgery (Thyroidectomy)

• Perform as (near) total thyroidectomy when surgery is chosen 4
• Limited but specific roles: large goitre causing compression symptoms, radioiodine refusal, or specific patient preference 7
• Rarely used for Graves' disease unless other options are unsuitable 7

Special Clinical Scenarios

Destructive Thyroiditis

• Self-limited condition requiring different management than Graves' disease 1, 3
• Beta-blockers for symptomatic relief only - antithyroid drugs are NOT indicated 1, 3
• Monitor with symptom evaluation and free T4 testing every 2 weeks 1
• Introduce thyroid hormone replacement if hypothyroidism develops (low free T4/T3, even if TSH not yet elevated) 1

Hyperthyroidism with Atrial Fibrillation

• Beta-blockers recommended for rate control unless contraindicated 1, 3
• Use non-dihydropyridine calcium channel antagonists (diltiazem or verapamil) when beta-blockers cannot be used 1, 3
• Normalize thyroid function before cardioversion - risk of relapse remains high otherwise 1, 3
• Antiarrhythmic drugs and cardioversion generally unsuccessful while thyrotoxicosis persists 1, 3
• Anticoagulation guided by CHA₂DS₂-VASc risk factors, not hyperthyroidism alone 1, 3

Subclinical Hyperthyroidism

**For TSH <0.1 mIU/L**: Consider treatment, particularly for patients >60 years or those with increased risk for heart disease, osteopenia, or osteoporosis 1

• 3-fold increased risk of atrial fibrillation over 10 years in patients >60 years 1
• Up to 3-fold increased cardiovascular mortality in individuals >60 years 1

For TSH 0.1-0.45 mIU/L: Routine treatment not recommended due to insufficient evidence of adverse outcomes 1

Drug Interactions Requiring Dose Adjustments

• Warfarin: Increased anticoagulation effect - adjust dose and monitor PT/INR closely 1, 5, 6
• Beta-blockers: May need dose reduction when patient becomes euthyroid 1, 5, 6
• Digoxin: Serum levels may increase when euthyroid - reduced dosage may be needed 5, 6
• Theophylline: Clearance decreases when euthyroid - reduced dose may be needed 1, 5, 6

Common Pitfalls to Avoid

• Never reduce methimazole based solely on suppressed TSH while free T4 remains elevated or high-normal - this leads to inadequate treatment and recurrent hyperthyroidism 1
• Do not attempt cardioversion in thyrotoxic patients without first achieving euthyroid state 1, 3
• Avoid using propylthiouracil as first-line agent except in first trimester pregnancy or methimazole intolerance due to severe hepatotoxicity risk 1, 4
• Do not overlook agranulocytosis warning signs - educate patients to report sore throat and fever immediately 1, 5, 6