Treatment for Multinodular Toxic Goiter
The initial treatment for multinodular toxic goiter should be methimazole to control hyperthyroidism, followed by definitive therapy with either radioiodine (I-131) or surgery, with the choice depending on goiter size, compressive symptoms, and patient factors. 1, 2
Initial Medical Management
- Start methimazole immediately to ameliorate hyperthyroid symptoms while planning definitive therapy 2
- Methimazole is FDA-approved specifically for toxic multinodular goiter when surgery or radioiodine is not immediately appropriate 2
- Use propylthiouracil only if the patient is intolerant to methimazole 3
- Confirm the diagnosis with suppressed TSH, elevated free T4/T3, and radioiodine uptake scan showing heterogeneous uptake in multiple nodules 1
Definitive Treatment Selection Algorithm
Choose Radioiodine (I-131) if:
- Goiter is small to moderate size (<100-130g) 4, 5
- No compressive symptoms present 6
- Patient refuses or has contraindications to surgery 7
- Radioiodine cures 92% of patients with 1-2 treatments and reduces thyroid volume by 43% 5
- Typical dose: 3.7 MBq/g thyroid tissue (approximately 25-30 mCi for most patients) 4, 5
Choose Surgery (Total Thyroidectomy) if:
- Large goiter (>100g) causing compressive symptoms (dysphagia, dyspnea, tracheal deviation) 6
- Substernal extension present 6
- Coexisting suspicious nodules requiring removal 1
- Patient has exophthalmos, as radioiodine may worsen eye disease 6
- Need for rapid resolution of hyperthyroidism 8
Critical Pre-Treatment Assessment
- Perform thyroid ultrasound on all patients to assess size, nodularity, and identify suspicious features 1
- Fine-needle aspiration is mandatory for nodules >1 cm or with suspicious ultrasound features to exclude malignancy 1
- Consider CT imaging if substernal extension or tracheal compression is suspected 6
- Never proceed to uptake scan without ultrasound evaluation first, as coexisting suspicious nodules may be missed 1
Alternative Long-Term Medical Management
- Long-term methimazole (60-100 months) is a valid alternative for patients <60 years who refuse or cannot undergo definitive therapy 9
- Maintenance dose typically 4-6 mg daily after initial control 9
- This approach maintains euthyroidism in 96% of patients with minimal side effects after the first 3 months 9
- Long-term methimazole is not inferior to radioiodine in effectiveness based on recent randomized trial data 9
Expected Outcomes and Follow-Up
After Radioiodine:
- Hypothyroidism develops in 14% within 5 years (6% without antithyroid pretreatment, 20% with pretreatment) 5
- Euthyroidism achieved in 37-52% of patients 9, 5
- Persistent/recurrent hyperthyroidism in 8-22% requiring additional treatment 9, 5
After Surgery:
- Lifelong thyroid hormone replacement is mandatory after total thyroidectomy 6
- TSH should be maintained in normal range (not suppressed, as C-cells lack TSH receptors) 10
- Regular monitoring of thyroid function tests required 6
Common Pitfalls to Avoid
- Do not assume all nodules are benign—biopsy prominent or suspicious nodules even in multinodular goiter 1
- Do not use radioiodine as first-line in patients with exophthalmos, as it may worsen eye disease 6
- Do not expect single radioiodine dose to cure very large goiters (>100g); consider surgery or adjunctive laser ablation before radioiodine 7, 4
- Do not suppress TSH with levothyroxine after treatment—maintain normal TSH levels 10