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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

  • Risk factors for malignancy: age <30, head or neck radiation, family history of thyroid cancer


  • TSH, Free T4, Thyroid U/S


  • If Low TSH: Likely a hyperfunctioning "hot" 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 intervals

    • 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 all

  • Nodules <1 cm with very ↓ suspicion OR pure cyst: no further imaging necessary

Last update: 2022-06-20 02:27:54