Management of Hyperfunctioning Thyroid Nodule
Radioactive iodine (RAI) therapy is the most appropriate treatment for this 40-year-old woman with a hyperfunctioning thyroid nodule. 1
Clinical Assessment and Diagnosis
- The patient presents with:
- 5mm non-tender, smooth, non-adherent thyroid nodule
- No enlargement over one year
- No lymphadenopathy
- Slightly elevated TSH
- Hyperfunctioning lesion on radionuclide testing
- Benign pattern on thyroid sonography
Treatment Options and Rationale
Radioactive Iodine (RAI) Therapy
- RAI is the first-line therapy for hyperfunctioning thyroid nodules with a significantly higher treatment response rate (94%) compared to alternatives 1
- Particularly appropriate for smaller nodules like this 5mm lesion
- Avoids surgical risks while effectively treating the hyperfunctioning tissue
- Can be administered on an outpatient basis with minimal side effects
Surgical Options
- Surgery (lobectomy) would be overly aggressive for this small, benign-appearing, stable nodule
- Surgery carries risks of complications including temporary or permanent recurrent laryngeal nerve damage, hypoparathyroidism, and bleeding
- Generally reserved for larger nodules (>3cm), compressive symptoms, or suspicious for malignancy
Thermal Ablation Techniques
- Radiofrequency ablation (RFA) has lower success rates (59%) compared to RAI for hyperfunctioning nodules 1
- While thermal ablation is recommended for benign dominant thyroid nodules causing clinical symptoms or nodules ≥2cm with gradual increase in size 2, this patient's nodule is small (5mm) and stable in size
- RFA shows excellent efficacy for volume reduction but is less effective for resolving hyperthyroidism compared to RAI 3
Antithyroid Medications
- Methimazole is indicated for preparation for definitive therapy (RAI or surgery) rather than as a standalone long-term treatment 4
- Would not address the underlying hyperfunctioning nodule
Implementation Considerations
- Prior to RAI therapy:
- Confirm absence of pregnancy
- Discontinue iodine-containing medications
- Consider low-iodine diet for 1-2 weeks before treatment
- Post-RAI monitoring:
- Follow thyroid function tests at 4-6 weeks, then every 3 months for the first year
- Monitor for potential development of hypothyroidism (occurs in approximately 19% of patients) 5
Common Pitfalls to Avoid
- Undertreatment: Inadequate RAI dosing may fail to resolve hyperthyroidism
- Overtreatment: Excessive RAI can lead to hypothyroidism requiring lifelong replacement
- Neglecting follow-up: Regular monitoring is essential as thyroid function may change over time
- Misdiagnosis: Ensure the nodule is truly autonomous before proceeding with definitive therapy
RAI therapy offers the best balance of efficacy and safety for this patient with a small hyperfunctioning thyroid nodule, with the highest success rate among non-surgical options.