What is the management of a patient with a history of toxic nodular goiter (TNG) who is non-adherent to anti-thyroid medication, such as methimazole (generic name), and presents with palpitations and tachycardia, and has a Thyroid-Stimulating Hormone (TSH) level of 0.2?

Management of Toxic Nodular Goiter with Poor Medication Adherence

Radioiodine therapy (RAI) is the most appropriate management for this patient with toxic nodular goiter who demonstrates poor adherence to antithyroid medications and presents with symptomatic hyperthyroidism (palpitations, tachycardia, and suppressed TSH). 1

Clinical Assessment and Rationale

The patient presents with:

• History of toxic nodular goiter
• Poor adherence to antithyroid medication
• Symptomatic hyperthyroidism (palpitations and tachycardia)
• Suppressed TSH (0.2)

These findings indicate persistent hyperthyroidism requiring definitive treatment rather than continued medical management that has already failed due to adherence issues.

Treatment Options Analysis

Option A & B: Surgical Management (Total or Near-Total Thyroidectomy)

• While surgery provides definitive treatment, it carries significant risks:
  • Anesthesia complications
  • Recurrent laryngeal nerve injury
  • Hypoparathyroidism
  • Postoperative bleeding
• Surgery should be reserved for specific indications such as large goiters with compressive symptoms, suspected malignancy, or patient preference

Option C: Antithyroid Drugs for 18 Months

• Methimazole is indicated for hyperthyroidism in toxic multinodular goiter 2
• However, this patient has already demonstrated poor adherence to antithyroid medications
• Long-term studies show extremely high relapse rates (95.1%) after discontinuation of antithyroid drugs in toxic multinodular goiter 3
• Continuing the same approach that has already failed is not appropriate

Option D: Radioiodine Therapy

• Provides definitive treatment with a single administration 1
• Eliminates concerns about medication adherence
• Avoids surgical risks
• Recommended by guidelines for patients with poor medication adherence 1
• Studies show RAI is effective in treating toxic multinodular goiter 4, 5

Implementation Plan

1. Pre-RAI Management:

   • Continue or initiate beta-blockers to control symptomatic tachycardia and palpitations until RAI takes effect 1
   • Consider short-term antithyroid medication (methimazole) to achieve euthyroidism before RAI 2
   • Discontinue methimazole 3-5 days before RAI administration to ensure adequate iodine uptake

2. RAI Administration:

   • Typical dose for toxic nodular goiter is higher than for Graves' disease
   • Patient should be counseled about radiation safety precautions

3. Post-RAI Follow-up:

   • Monitor thyroid function tests at 4-6 weeks, then every 3 months for the first year
   • Continue beta-blockers until thyroid function normalizes
   • Be vigilant for development of hypothyroidism (occurs in approximately 41% of patients following RAI for toxic nodular goiter) 1
   • Initiate levothyroxine if hypothyroidism develops

Key Considerations

• Radioiodine therapy provides a permanent solution for patients with adherence issues
• While long-term methimazole has been shown to be effective in some studies 5, it requires consistent adherence which this patient has not demonstrated
• The patient's symptomatic presentation with tachycardia indicates the need for definitive treatment rather than continued attempts at medical management
• Beta-blockers should be used to control cardiac symptoms until the RAI takes effect 1

The correct answer is D. Radio iodine therapy.