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 and tachycardia with TSH of 0.2). 1

Rationale for Radioiodine Therapy (Option D)

• Patient-specific factors favoring RAI:

  • History of poor medication adherence (not taking antithyroid drugs regularly)
  • Current symptomatic hyperthyroidism (palpitations and tachycardia)
  • Suppressed TSH level (0.2) indicating ongoing hyperthyroidism
  • Need for definitive treatment that doesn't rely on daily medication compliance

• Benefits of RAI for toxic nodular goiter:

  • Provides definitive treatment with a single administration
  • Eliminates concerns about medication adherence
  • Avoids surgical risks associated with thyroidectomy
  • Recommended by guidelines for patients with poor adherence to antithyroid medications 1

Why Other Options Are Less Appropriate

1. Total Thyroidectomy (Option A):

   • Carries surgical risks including recurrent laryngeal nerve damage and hypoparathyroidism
   • Requires hospitalization and recovery period
   • Excessive for a patient whose primary issue is medication non-adherence

2. Near-total Thyroidectomy (Option B):

   • Similar surgical risks to total thyroidectomy
   • Still an overly invasive approach when a non-surgical definitive treatment (RAI) is available

3. Antithyroid drugs for 18 months (Option C):

   • Patient has already demonstrated poor adherence to antithyroid medication
   • Continuing the same approach is unlikely to succeed
   • Research shows that antithyroid drugs do not provide permanent remission in toxic nodular goiter 2

Management Algorithm

1. Pre-RAI preparation:

   • Continue or restart antithyroid drugs (methimazole) temporarily to achieve euthyroidism before RAI 3
   • Administer beta-blockers to control cardiac symptoms (palpitations and tachycardia) until RAI takes effect 1
   • Discontinue methimazole 3-5 days before RAI administration to ensure adequate radioiodine uptake

2. RAI administration:

   • Single dose of radioactive iodine (typically 10-30 mCi depending on gland size)
   • Provide radiation safety instructions

3. Post-RAI follow-up:

   • Continue beta-blockers until symptoms resolve
   • Monitor thyroid function tests at 4-6 weeks, then every 2-3 months for the first year
   • Watch for development of hypothyroidism, which occurs in approximately 41% of patients following RAI for toxic nodular goiter 1
   • Initiate levothyroxine if hypothyroidism develops

Important Considerations

• Radioiodine therapy has been shown to be superior to long-term methimazole in achieving sustained euthyroidism in patients with toxic nodular goiter 4
• Patients should be counseled that hypothyroidism may develop following RAI, requiring lifelong thyroid hormone replacement
• Special attention should be given to cardiac monitoring in patients with tachycardia and palpitations, as cardiac complications are common in untreated hyperthyroidism 2

Pitfalls to Avoid

• Continuing antithyroid drugs too close to RAI administration (reduces effectiveness)
• Failing to provide adequate beta-blockade for symptom control during the transition period
• Inadequate follow-up, which may lead to unrecognized hypothyroidism or persistent hyperthyroidism
• Underestimating the importance of definitive treatment in a patient with demonstrated non-adherence