What is the recommended treatment for a patient with toxic nodular goitre?

Treatment of Toxic Nodular Goiter

Definitive treatment with either radioactive iodine (RAI) therapy or surgery is recommended for toxic nodular goiter, with methimazole used as bridging therapy to achieve euthyroidism before definitive treatment. 1, 2

Initial Management and Diagnosis

• Begin with serum TSH measurement—when suppressed (TSH <0.5 mU/L), proceed immediately with thyroid ultrasound to evaluate morphology, nodule characteristics, and gland size 3, 1
• Measure free T3 and free T4 to determine hyperthyroidism severity, as toxic nodular goiter can present with isolated T3 toxicosis despite minimal T4 elevation 3, 1
• Perform radioiodine uptake scan with I-123 (preferred over I-131 for superior image quality) to confirm autonomous function and differentiate toxic multinodular goiter from toxic adenoma, Graves' disease, or thyroiditis 4, 3, 1
• Compare ultrasound findings with radionuclide scan results to identify any nodules requiring fine needle aspiration biopsy, as "hot" nodules are not automatically benign 3, 1

Bridging Medical Therapy

• Initiate methimazole to ameliorate hyperthyroid symptoms while preparing for definitive therapy 1, 2
• Methimazole is FDA-approved for toxic multinodular goiter when surgery or RAI is not immediately appropriate, and for symptom control before thyroidectomy or RAI 2
• Monitor for agranulocytosis and allergic reactions during antithyroid drug therapy 1
• If methimazole is not tolerated, propylthiouracil is the alternative antithyroid drug 5
• Continue methimazole until 6 days before RAI administration, but avoid long-term use as sole therapy since it does not provide cure 1, 6

Definitive Treatment Selection Algorithm

Choose Surgery (Total or Near-Total Thyroidectomy) when:

• Large goiter causing compressive symptoms (dysphagia, dyspnea, orthopnea, dysphonia) 1, 7
• Suspicious nodules requiring histological evaluation for malignancy 1, 7
• Substernal extension (obtain CT scan to assess extent) 1
• Young patients with long life expectancy 1
• Previous neck surgery or radiation making reoperation consideration necessary 1
• Patient preference for rapid cure—surgery achieves euthyroidism more quickly than RAI, with 93% cure rate after one procedure 8, 7, 9

Choose Radioactive Iodine Therapy when:

• Elderly patients or those with significant surgical comorbidities 1, 7
• Smaller goiter without significant compressive symptoms 1, 7
• Patient preference to avoid surgery 1
• RAI achieves 89% cure rate with single treatment, though approximately 5% of patients require three or more treatments 8
• Avoid iodinated contrast agents before RAI as they interfere with iodine uptake 1

Post-Treatment Monitoring and Outcomes

• Monitor thyroid function tests every 4-6 weeks initially, then every 3-6 months after RAI therapy 1
• Initiate levothyroxine replacement immediately after total thyroidectomy 1
• Expect hypothyroidism in 58-64% of patients treated with RAI and 64% after surgery at long-term follow-up—the incidence is surprisingly similar between modalities 8
• Monitor calcium levels post-surgery for potential hypoparathyroidism (occurred in 7% of one surgical series) 9
• Recurrent laryngeal nerve injury occurs in approximately 3% of surgical cases 9

Critical Pitfalls to Avoid

• Never delay treatment—untreated toxic nodular goiter leads to cardiac complications, particularly atrial fibrillation in elderly patients 1
• Never proceed directly to uptake scan without checking TSH first—this wastes resources and has low diagnostic value in euthyroid patients 3, 1
• Never rely on radionuclide scanning alone to determine malignancy risk—it has low positive predictive value for cancer and cannot replace ultrasound evaluation with FNA for suspicious nodules 3, 1
• Never skip ultrasound before uptake scan—coexisting thyroid nodules requiring biopsy for malignancy can be missed, and structural abnormalities affecting treatment decisions may go undetected 4
• Never use levothyroxine suppression therapy in toxic nodular goiter—it is contraindicated when TSH is already suppressed and risks worsening hyperthyroid symptoms 7
• Recognize that up to 5 treatments may be needed for RAI cure in complex cases—this is rarely described but indicates treatment can be more challenging than expected 8

Long-Term Considerations

• Patients experience worse thyroid-related quality of life scores across a broad spectrum compared to the general population, even after achieving euthyroidism 8
• Symptoms often persist long after biochemical euthyroidism is achieved, with long-term cognitive and quality of life impairments documented 8
• The chronic nature of hyperthyroidism from toxic nodular goiter means that achieving biochemical cure does not guarantee complete symptom resolution 8