What is the best next step when a thyroid ultrasound reveals a non-toxic nodular goiter?

Management of Non-Toxic Nodular Goiter

The best next step when thyroid ultrasound reveals a non-toxic nodular goiter is to evaluate nodule characteristics using the ACR TI-RADS criteria to determine which nodules require fine-needle aspiration biopsy (FNAB) based on their size and suspicious features. Thyroid function tests should be performed first to confirm euthyroid status, followed by ultrasound-guided FNAB for suspicious nodules that meet size criteria according to ACR TI-RADS risk stratification. 1

Diagnostic Evaluation Algorithm

1. Confirm euthyroid status

   • Measure serum TSH, free T4, and free T3 to verify normal thyroid function 1
   • If TSH is subnormal, the patient has thyrotoxicosis and requires different management 1

2. Detailed ultrasound assessment

   • Characterize each nodule for risk of malignancy using ACR TI-RADS criteria 1
   • Document nodule size, location, composition, echogenicity, margins, calcifications, and shape 1
   • Evaluate for suspicious features that increase malignancy risk 1

3. Select nodules for FNAB based on ACR TI-RADS criteria

   • Higher TI-RADS score (more suspicious features) = lower size threshold for biopsy 1
   • Prioritize dominant nodules and those with suspicious sonographic features 1

4. Assess for compression symptoms

   • Evaluate for dyspnea, orthopnea, obstructive sleep apnea, dysphagia, and dysphonia 1, 2
   • These symptoms indicate mass effect on the trachea or esophagus requiring intervention 1, 2

Management Based on Findings

For nodules with benign cytology:

• If asymptomatic with normal TSH:

  • Annual clinical follow-up with TSH determination and thyroid palpation 3
  • Periodic ultrasound monitoring to assess for growth 4
  • Levothyroxine suppression therapy is generally not recommended for non-toxic multinodular goiter 5, 3

• If symptomatic (compression symptoms):

  • Surgical intervention is the preferred treatment 3, 4
  • CT scan is recommended to evaluate substernal extension and tracheal compression before surgery 1, 2

For nodules with suspicious or malignant cytology:

• Refer for surgical management 4
• Patients with suspicious (indeterminate) cytology generally require surgery unless autonomous function can be confirmed by scintigraphy 4

Special Considerations

• Substernal extension:

  • If goiter extends substernally, CT is superior to ultrasound for evaluating the extent and degree of tracheal compression 1, 2
  • CT is preferred over MRI due to less respiratory motion artifact 1

• Radioactive iodine therapy:

  • May be considered as an alternative to surgery for volume reduction in select cases 4, 6
  • Caution: Late development of autoimmune hyperthyroidism has been reported after radioiodine treatment for non-toxic nodular goiter 6

• Thermal ablation:

  • Emerging option for selected patients with benign nodules 1
  • Regular follow-up required to monitor volume reduction rate and symptom improvement 1

Common Pitfalls to Avoid

• Overlooking suspicious nodules in multinodular goiter:

  • All nodules should be evaluated, not just the largest 4, 7
  • Risk of malignancy in multinodular goiter is similar to that in solitary nodules 7

• Inappropriate use of levothyroxine:

  • Not indicated for suppression of benign thyroid nodules and non-toxic diffuse goiter in iodine-sufficient patients 5
  • May induce hyperthyroidism and has potential for serious adverse effects 5, 3

• Inadequate imaging for large goiters:

  • Relying solely on ultrasound for large goiters with suspected substernal extension 1, 2
  • CT provides superior evaluation of substernal extension and tracheal compression 1, 2