Thyroid Nodules

Thyroid Nodules – Terra Swanson


  • ~50% of adults will have a thyroid nodule on ultrasound
  • Benign: goiter, cyst, inflammatory, Hashimoto’s, follicular adenoma (microadenoma)
  • Malignant: follicular, papillary, medullary, anaplastic, metastatic, thyroid lymphoma
  • RF for malignancy: Age <30 years; hx of head or neck radiation; family Hx of thyroid cancer



  • Initial work-up after a nodule is found (either clinically or incidentally on imaging):
    • TSH, Free T4
    • Thyroid US



  • If Low TSH: Likely a hyperfunctioning nodule (benign in 95% of cases)
    • Order Iodine-123 or technetium-99m thyroid scan
      • If hyperfunctioning measure T3/free T4 if , treat for hyperthyroidism
      • If non-functioning proceed as if TSH were normal
  • Normal or elevated TSH:
    • FNA indicated based on U/S findings listed below (determined by TI-RADS system)
      • Nodules >1 cm that have high- or intermediate-suspicion pattern
      • Nodules >1.5 cm that have low-suspicion pattern
      • Nodules >2 cm that have very-low-suspicion pattern
    • FNA cytology determines the plan of action:
      • Benign → periodic US monitoring at 12-24 months, then at increasing interval
      • Indeterminate → repeat FNA in 3-12 months
      • Malignant surgical referral
  • Nodules that do not meet FNA criteria, US findings determine the timing for follow-up imaging:
    • High suspicion: 6-12 months
    • Low to intermediate suspicion: 12-24 months
    • Nodules >1 cm with very suspicion OR pure cyst:  >24 months if at al
  • ​​​​​​​Nodules <1 cm with very suspicion OR pure cyst: no further imaging necessary