What are the treatment options for multinodular goitre based on its size, symptoms, thyroid function, and suspicion of malignancy?

Treatment of Multinodular Goitre

The treatment of multinodular goitre depends primarily on thyroid function status, presence of compressive symptoms, nodule size and ultrasound characteristics, and exclusion of malignancy—with observation appropriate for asymptomatic euthyroid patients after proper evaluation, while surgery or radioiodine are reserved for symptomatic, hyperfunctioning, or suspicious cases. 1

Initial Diagnostic Evaluation

Measure serum TSH as the first-line test in all patients with multinodular goitre to determine thyroid functional status and guide subsequent management. 1, 2

• If TSH is low or suppressed, measure free T4 and free T3 to assess for hyperthyroidism, and perform thyroid scintigraphy to identify autonomously functioning nodules (common in iodine-deficient regions). 1, 3, 2
• If TSH is elevated, measure thyroid peroxidase antibodies (TPOAbs) and free T4 to evaluate for autoimmune thyroiditis. 1
• If TSH is normal, proceed with ultrasound-guided risk stratification and selective fine-needle aspiration. 1

Perform high-resolution thyroid ultrasound in every patient with palpable multinodular goitre to characterize nodule size, composition, and sonographic risk features. 1, 2

Fine-Needle Aspiration Strategy

The primary clinical challenge is to exclude malignancy, as most multinodular goitres are benign and asymptomatic. 1

Size and Risk-Based FNA Indications

• Do not biopsy nodules <5 mm regardless of appearance; monitor with ultrasound surveillance only. 1, 2
• Nodules 5–10 mm: Perform FNA only if high-risk ultrasound features are present (marked hypoechogenicity, microcalcifications, irregular margins, taller-than-wide shape) and there are pathologic lymph nodes, extrathyroidal extension, or personal/family history of thyroid cancer. 1, 2
• Nodules >10 mm with intermediate risk features (slightly hypoechoic, smooth or ill-defined margins): Perform FNA when the nodule lacks a definitively benign appearance. 1, 2
• Nodules ≥20 mm that are spongiform, isoechoic, or predominantly cystic (>50%): Perform FNA only if progressively enlarging or in the absence of suspicious features. 1, 2

Critical Exceptions

Do not perform FNA on nodules that are functioning ("hot") on scintigraphy and lack suspicious ultrasound features, as malignancy is exceedingly rare in autonomously functioning nodules. 1, 2, 4

Limit biopsies to a maximum of two nodules in a multinodular gland; prioritize those with the highest ultrasound risk category and size criteria. 2, 4

Management Based on Cytology and Clinical Status

Benign Cytology (Bethesda II)

Most patients with benign multinodular goitre require no treatment; clinical and ultrasound follow-up is the standard approach. 1

• Perform the first follow-up ultrasound at 12 months, then at 24 months if unchanged, then every 2–3 years until 5–7 years. 1, 5
• Repeat FNA is indicated if suspicious clinical or ultrasound features develop, or if nodule volume increases by >50% (the threshold that exceeds interobserver variability). 1
• In asymptomatic nodules with repeatedly benign cytology and no suspicious features, routine follow-up may be discontinued. 1, 2

Medical Therapy

Levothyroxine suppressive therapy is not recommended for euthyroid patients with benign multinodular goitre, as it lacks efficacy and carries risks of iatrogenic hyperthyroidism. 1, 2

Exceptions where non-suppressive levothyroxine may be considered:

• Young patients in iodine-deficient geographic regions with small nodular goitre and high-normal TSH levels; iodine supplementation is also recommended in these areas. 1, 2
• Young patients with subclinical hypothyroidism due to autoimmune thyroiditis should receive levothyroxine replacement (not suppression). 1, 2

Levothyroxine is not recommended to prevent recurrence after lobectomy when TSH remains in the normal range. 1, 2

Indications for Definitive Treatment

Surgery

Surgery is indicated when:

• Compressive symptoms are present and clearly associated with the goitre (dysphagia, dyspnea, neck tightness, airway obstruction). 1, 6
• Large goitre size (>80 g), substernal or retrosternal extension, or need for rapid correction of thyrotoxic state. 3
• Suspicious ultrasound features emerge despite benign FNA findings. 1, 2
• Coexisting thyroid cancer is suspected or confirmed, or coexisting hyperparathyroidism requires concurrent surgery. 3
• Cosmetic concerns or patient preference after shared decision-making. 6

All patients undergoing total thyroidectomy for compressive symptoms achieve resolution, whereas only 46% of patients treated with radioiodine experience improvement in compressive symptoms. 3

Surgical complications include permanent hypoparathyroidism (<2%) and recurrent laryngeal nerve injury (<2%) when performed by high-volume thyroid surgeons. 3

Radioiodine Therapy

Radioiodine is appropriate for hyperfunctioning or symptomatic goitre, particularly in patients with:

• Advanced age, significant comorbidity, or prior neck surgery/scarring. 3
• Small goitre size with sufficient radioactive iodine uptake (RAIU). 3
• Patients who decline surgery or lack access to a high-volume thyroid surgeon. 3, 2

Before radioiodine therapy, perform FNA on coexistent cold (non-functioning) nodules to exclude malignancy. 1, 2

Limitations of radioiodine:

• Large goitres treated with high-activity radioiodine decrease in size by only 30–50%, and compressive symptoms improve in less than half of patients. 3
• Progressive hypothyroidism occurs in 3% at 1 year, 28% at 5 years, 46% at 10 years, and 64% at 24 years. 3
• Hypothyroidism develops more rapidly in patients with incomplete TSH suppression or antithyroid antibodies. 3

Absolute contraindications to radioiodine include pregnancy, lactation, coexisting thyroid cancer, inability to comply with radiation safety guidelines, and females planning pregnancy within 4–6 months. 3

Minimally Invasive Procedures

Percutaneous ethanol injection (PEI) is the first-line treatment for relapsing benign cystic thyroid lesions and is safe and effective for cysts and complex nodules with a large fluid component. 1, 2

• Carefully sample the solid component of complex lesions before performing PEI. 1, 2
• PEI is not recommended for solid nodules (whether hyperfunctioning or not) or for multinodular goitres. 1, 2

US-guided thermal ablation (laser or radiofrequency) may be considered for solid or complex nodules that are symptomatic, progressively enlarging, or cause cosmetic concern. 1

• Repeat FNA for cytologic confirmation before thermal ablation treatment. 1, 2

Common Pitfalls and Caveats

Avoid the misconception that all nodules in a multinodular goitre require biopsy; use size and ultrasound risk stratification to select only the most suspicious nodules. 1, 2, 4

Do not assume that a large goitre automatically requires surgery; asymptomatic euthyroid patients with benign cytology can be safely observed. 1, 7

Recognize that radioiodine is less effective for compressive symptoms than surgery, and goitre size reduction is modest; surgery is superior when compression is the primary indication. 3

Be aware that levothyroxine suppression lacks evidence of benefit in euthyroid multinodular goitre and may cause harm (atrial fibrillation, bone loss). 1, 2

Always perform FNA under ultrasound guidance; palpation-guided FNA has unacceptably high nondiagnostic rates and lower accuracy. 1, 2, 4

In elderly patients with subclinical hyperthyroidism from toxic multinodular goitre, definitive treatment (radioiodine or surgery) is preferred over observation when TSH is <0.1 mIU/L, especially if cardiovascular disease, atrial fibrillation, or osteoporosis is present. 8