Thyroid Nodule Evaluation (ATA 2015)

Algorithm Steps

1. ▶

   Start

   Thyroid Nodule Detected

   Palpated or incidentally found on imaging

   1. ●

      Action

      Initial Evaluation

      History and TSH

      • History: radiation exposure, family history thyroid cancer, compressive symptoms
      • TSH level: first-line test for all thyroid nodules
      • If TSH low: radionuclide scan (may be hot nodule)
      • If TSH normal/high: proceed to ultrasound
      1. ◆

         Decision

         TSH Level

         Determines next step

         1. ●

            Action

            Low TSH (Hyperthyroid)

            Consider autonomous nodule

            • Radionuclide scan (I-123 or Tc-99m)
            • Hot nodule: low malignancy risk, no FNA needed
            • Treat hyperthyroidism (radioiodine, surgery, or antithyroid)
            • Cold nodule: proceed to ultrasound/FNA
            1. ●

               Action

               Normal/High TSH

               Thyroid ultrasound required

               • High-resolution ultrasound of thyroid
               • Evaluate nodule sonographic features
               • Check for suspicious lymph nodes
               • Measure nodule dimensions accurately
               1. ◆

                  Decision

                  ACR TI-RADS Classification

                  Risk stratification by ultrasound features

                  • TR1 (Benign): cystic, no FNA
                  • TR2 (Not suspicious): No FNA regardless of size
                  • TR3 (Mildly suspicious): FNA if ≥2.5 cm
                  • TR4 (Moderately suspicious): FNA if ≥1.5 cm
                  • TR5 (Highly suspicious): FNA if ≥1 cm
                  1. ✓

                     Outcome

                     Observation

                     Repeat ultrasound in 12-24 months based on TI-RADS

                  2. ●

                     Action

                     FNA Biopsy Indicated

                     Ultrasound-guided preferred

                     • TI-RADS 3: ≥2.5 cm
                     • TI-RADS 4: ≥1.5 cm
                     • TI-RADS 5: ≥1 cm
                     • Any size if suspicious nodes or vocal cord paralysis
                     • Repeat if non-diagnostic (up to 3 attempts)
                     1. ◆

                        Decision

                        Bethesda Cytology Result

                        6-category system

                        • I: Non-diagnostic (repeat FNA)
                        • II: Benign (follow-up US)
                        • III: AUS/FLUS (repeat FNA or molecular testing)
                        • IV: Follicular neoplasm (surgery or molecular)
                        • V: Suspicious for malignancy (surgery)
                        • VI: Malignant (surgery)
                        1. ✓

                           Outcome

                           Benign (Bethesda II)

                           Follow with ultrasound at 12-24 months, then as clinically indicated

                        2. ●

                           Action

                           Indeterminate (Bethesda III/IV)

                           Molecular testing or surgery

                           • Molecular testing (ThyroSeq, Afirma): may avoid surgery if benign
                           • If suspicious molecular markers: surgery
                           • Diagnostic lobectomy if molecular not done
                           • Discuss options with patient
                           1. ●

                              Action

                              Endocrinology Referral

                              Consider for complex cases

                              • Indeterminate cytology (Bethesda III/IV)
                              • Multiple nodules or MNG
                              • Hyperthyroidism requiring treatment
                              • Family history of thyroid cancer
                        3. ⚠

                           Warning

                           Suspicious/Malignant (V/VI)

                           Surgical referral

                           • Endocrine surgery referral
                           • Total thyroidectomy or lobectomy (based on size, features)
                           • Staging workup if confirmed cancer
                           • Risk stratification for adjuvant RAI