Hyperthyroidism Management
First-Line Treatment: Methimazole with Beta-Blocker Support
Methimazole is the preferred first-line antithyroid drug for hyperthyroidism due to superior efficacy and safety profile, with immediate beta-blocker therapy for symptomatic control. 1
Initial Management Algorithm
Immediate Symptomatic Control
- Initiate beta-blocker therapy immediately while confirming diagnosis and determining etiology 2
- Atenolol 25-50 mg daily or propranolol are preferred agents, titrating to heart rate <90 bpm if blood pressure allows 1, 2
- Beta-blockers provide rapid relief of tachycardia, tremor, anxiety, and heat intolerance within hours 1
- If beta-blockers are contraindicated, use non-dihydropyridine calcium channel antagonists (diltiazem or verapamil) as alternatives 1, 2
- Digoxin is less effective when adrenergic tone is high and should be avoided as monotherapy 2
Antithyroid Drug Selection
- Methimazole is the drug of choice except during first trimester of pregnancy 1, 3
- Starting dose: 10-30 mg daily as a single dose 4
- Propylthiouracil is reserved for:
Treatment Monitoring Strategy
Critical Monitoring Parameters
- Monitor free T4 or free T3 index every 2-4 weeks during initial treatment 1
- Target: Maintain free T4/T3 in the high-normal range using the lowest effective dose 1
- Do NOT target TSH normalization—TSH may remain suppressed for months even after achieving euthyroidism 1
Common Pitfall 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
Life-Threatening Adverse Effects Requiring Immediate Action
Agranulocytosis (Most Critical)
- Occurs within first 3 months of thioamide therapy 1
- Presents with sore throat and fever 1
- Immediate action: Obtain CBC and discontinue drug immediately 1, 3, 5
- Patients must report sore throat, fever, or general malaise immediately 3, 5
Hepatotoxicity (Especially with Propylthiouracil)
- Monitor for: Fever, nausea, vomiting, right upper quadrant pain, dark urine, jaundice 1, 5
- Immediate drug discontinuation if suspected 1
- Propylthiouracil can cause severe liver failure requiring transplantation 5, 6
Vasculitis
- Can be life-threatening 1
- Watch for: Skin changes, hematuria, respiratory symptoms 1
- Patients must report new rash, hematuria, decreased urine output, dyspnea, or hemoptysis promptly 3, 5
Special Clinical Scenarios
Destructive Thyroiditis (Including Immune Checkpoint Inhibitor-Induced)
- Self-limited condition requiring different management than Graves' disease 1, 2
- Beta-blockers for symptomatic relief only—antithyroid drugs are NOT indicated 1, 2
- Monitor with symptom evaluation and free T4 testing every 2 weeks 1
- Introduce thyroid hormone replacement if patient becomes hypothyroid (low free T4/T3, even if TSH not yet elevated) 1
- Continue immune checkpoint inhibitor therapy in most cases—thyroid dysfunction rarely requires treatment interruption 2
Pregnancy Management
- First trimester: Propylthiouracil is preferred due to methimazole's association with congenital malformations (aplasia cutis, choanal/esophageal atresia) 1, 3, 4
- After first trimester: Switch back to methimazole due to propylthiouracil's hepatotoxicity risk 1, 5
- Goal: Maintain FT4 or free T3 index in high-normal range using lowest possible thioamide dosage 1
- Both drugs are compatible with breastfeeding 1
Atrial Fibrillation Complicating Hyperthyroidism
- Beta-blockers for rate control unless contraindicated 1, 2
- Anticoagulation based on CHA₂DS₂-VASc risk factors, not hyperthyroidism alone 1, 2
- Normalize thyroid function before cardioversion—risk of relapse remains high otherwise 1, 2
- Never attempt cardioversion in thyrotoxic patients without first achieving euthyroid state 1
- Antiarrhythmic drugs and cardioversion are generally unsuccessful while thyrotoxicosis persists 1, 2
Definitive Treatment Options
Radioactive Iodine (I-131) Ablation
- Absolutely contraindicated in pregnancy and breastfeeding 1
- Pregnancy must be avoided for 4 months following administration 1, 7
- Potential risk of worsening Graves' ophthalmopathy—corticosteroid cover may reduce this risk 1, 7
- Treatment of choice for toxic nodular goitre 7, 8
- Growing use as first-line therapy for Graves' disease 7
Surgery (Thyroidectomy)
- Limited but specific roles: 7
- Radioiodine refused
- Large goitre causing compressive symptoms
- Rarely used in Graves' disease
- Perform as (near) total thyroidectomy 6
Drug Interactions Requiring Dose Adjustments
When Patient Becomes Euthyroid
- Warfarin: Increased anticoagulation effect—adjust dose and monitor PT/INR closely 1, 3, 5
- Beta-blockers: May need dose reduction 1, 3, 5
- Theophylline: Clearance decreases—reduce dose 1, 3, 5
- Digoxin: Serum levels may increase—reduce dose 3, 5
Subclinical Hyperthyroidism Treatment Thresholds
TSH <0.1 mIU/L
- Consider treatment for: 1
- Patients >60 years (3-fold increased risk of atrial fibrillation over 10 years)
- Those with increased risk for heart disease
- Osteopenia or osteoporosis risk
- Estrogen-deficient women (bone loss risk)
TSH 0.1-0.45 mIU/L
- Routine treatment NOT recommended due to insufficient evidence of adverse outcomes 1
- Consider treatment only in elderly with cardiovascular risk factors 1