Adult with a thyroid nodule
Palpable, or found by chance on imaging (CT, MRI, PET or carotid ultrasound). For adults 18 years and over.
All Pathways
Family MedicineDiagnostic
Thyroid Nodule Evaluation (ATA 2015)
Thyroid Nodule Evaluation (ATA 2015): Adult with a thyroid nodule → Urgent referral: red flags, or age under 18 → History, examination and TSH → Pregnan...
Pathway Overview
14 steps
Algorithm Steps
14 total
01Start 02Warning Urgent referral: red flags, or age under 18
Do not wait for the full work-up
- Stridor or breathing difficulty: send to the emergency department now
- Rapid growth, new hoarseness or vocal cord palsy, hard fixed mass, or enlarged neck nodes: urgent referral to a thyroid or head and neck surgeon
- Child or adolescent: refer to paediatric endocrinology. Malignancy risk is higher and adult size cut-offs do not apply
03Action History, examination and TSH
All patients
- Risk factors: head and neck radiation in childhood, total body radiation, family history of thyroid cancer or MEN2 or other thyroid cancer syndrome
- Examine the thyroid and the neck lymph nodes
- Measure TSH in all patients. Thyroglobulin is not recommended
- High TSH: check free T4 and manage hypothyroidism. Continue the nodule work-up with ultrasound
- Ask about pregnancy and breastfeeding
04Warning Pregnant or breastfeeding: no radionuclide scan, no radioiodine
A low TSH in the first trimester can be normal (hCG effect)
- Do not do a thyroid scan. Discuss a low TSH with endocrinology or obstetric medicine
- Ultrasound and FNA criteria are the same as for non-pregnant adults
- If TSH stays suppressed after 16 weeks, FNA can wait until after pregnancy and breastfeeding; then scan if TSH is still low
05Action Low TSH (not pregnant): free T4, T3 and thyroid scan
Looks for a hyperfunctioning (hot) nodule. Normal or high TSH: no scan, go to ultrasound
- Free T4 and free T3
- Radionuclide thyroid scan (Tc-99m pertechnetate or I-123). Confirm the patient is not pregnant
- Hot nodule that matches the ultrasound nodule: rarely cancer, FNA not needed
- Overt or subclinical hyperthyroidism: refer to endocrinology for treatment
- Warm or cold nodules, and other nodules: use the ultrasound FNA criteria
06Action Ultrasound of the thyroid and neck lymph nodes: all patients
Normal or high TSH: ultrasound is the first imaging test
- Size of each nodule in 3 dimensions, and its location
- Sonographic pattern of each nodule (ATA pattern or ACR TI-RADS level)
- Survey the central and lateral neck lymph nodes
- Multiple nodules: assess each nodule of 1 cm or more on its own
07Decision Does the nodule meet FNA criteria?
FNA if: ATA high or intermediate suspicion 1 cm or more, low 1.5 cm or more, very low 2 cm or more (optional). ACR TR5 1 cm or more, TR4 1.5 cm or more, TR3 2.5 cm or more. Focal FDG-PET uptake: FNA at 1 cm or more, any pattern. Suspicious neck node: FNA at any size
- Use the system in the ultrasound report. Size is the largest dimension
- ATA 2015: high or intermediate suspicion, FNA at 1 cm or more; low suspicion, 1.5 cm or more; very low suspicion (e.g. spongiform), consider FNA at 2 cm or more, or observe
- ACR TI-RADS: TR5, FNA at 1 cm or more; TR4, 1.5 cm or more; TR3, 2.5 cm or more; TR1 and TR2, no FNA
- Purely cystic nodule: no diagnostic FNA
- Suspicious neck lymph node: FNA of the node, whatever the nodule size
- Focal uptake on FDG-PET (about 1 in 3 is cancer): FNA if 1 cm or more, whatever the ultrasound pattern. Under 1 cm: follow as high suspicion. Diffuse uptake with thyroiditis on ultrasound: no FNA
- Suspected extrathyroidal extension: FNA or specialist referral at any size
- Hot nodule on scan: no FNA
- Clinical risk factors (e.g. childhood radiation, family history): FNA can be considered at a smaller size
- Does not meet FNA criteria
08Outcome Does not meet FNA criteria: ultrasound follow-up
Repeat FNA if the nodule later meets the criteria (growth or new suspicious features)
- ATA high suspicion: repeat ultrasound in 6 to 12 months
- ATA low or intermediate suspicion: consider repeat ultrasound at 12 to 24 months
- ATA very low suspicion or pure cyst over 1 cm: if repeated, at 24 months or later. Very low suspicion or pure cyst 1 cm or less: no routine follow-up
- ACR TI-RADS: TR3 of 1.5 cm or more at 1, 3 and 5 years; TR4 of 1 cm or more at 1, 2, 3 and 5 years; TR5 of 0.5 cm or more every year for up to 5 years
- Meets FNA criteria
09Action Meets FNA criteria: ultrasound-guided FNA
Cytology reported with the Bethesda system (2023)
- Ultrasound-guided FNA by an experienced operator
- Several nodules: choose by pattern and size, not only the largest
- Anticoagulant or antiplatelet drug: tell the proceduralist before the FNA
10Decision Bethesda cytology category
The Bethesda 2023 (3rd edition) category decides the next step
- I: Nondiagnostic
- II: Benign
- III: Atypia of undetermined significance (AUS)
- IV: Follicular neoplasm
- V: Suspicious for malignancy
- VI: Malignant
- I
11Action Bethesda I (nondiagnostic): repeat ultrasound-guided FNA
Most nondiagnostic nodules are benign, but do not stop follow-up
- Repeat FNA with ultrasound guidance, with on-site cytology review if available
- Nondiagnostic again, and no high-suspicion pattern: close ultrasound follow-up or surgery for diagnosis
- High-suspicion pattern, growth over 20% in 2 dimensions, or clinical risk factors: refer for surgery for diagnosis
- II
12Outcome Bethesda II (benign): no immediate treatment; ultrasound follow-up
High-suspicion ultrasound pattern: repeat ultrasound and FNA within 12 months. Others: follow-up by pattern
- Low or intermediate suspicion: repeat ultrasound at 12 to 24 months; repeat FNA if it grows or new suspicious features appear
- Very low suspicion: if ultrasound is repeated, at 24 months or later
- Second benign FNA: stop ultrasound surveillance of that nodule for cancer risk
- Growth means a 20% increase in at least 2 dimensions (at least 2 mm), or over 50% in volume
- Compressive symptoms or a large growing nodule (over 4 cm): refer to a surgeon
- III or IV
13Action Bethesda III (AUS) or IV (follicular neoplasm): specialist referral
Decide with the patient, using clinical risk, ultrasound pattern and preference
- III (AUS): repeat FNA and, where available, molecular testing; then surveillance or diagnostic surgery
- IV (follicular neoplasm): diagnostic lobectomy is the standard; molecular testing where available
- Australia: molecular testing of FNA samples is not Medicare-funded
- V or VI
14Warning Bethesda V (suspicious) or VI (malignant): refer to a thyroid surgeon
Manage as likely thyroid cancer (multidisciplinary team). Anaplastic carcinoma or lymphoma on cytology: urgent referral within days
- Refer to a thyroid or head and neck surgeon; surgery is usual. Neck lymph node ultrasound before surgery
- Medullary carcinoma on cytology: calcitonin, CEA and RET testing; exclude phaeochromocytoma before any surgery
- Active surveillance may be an option for very low-risk papillary microcarcinoma, high surgical risk or short life expectancy
Guideline Source
2015 ATA Management Guidelines for Adult Patients with Thyroid Nodules and Differentiated Thyroid Cancer (nodule sections); ACR TI-RADS 2017; Bethesda System 2023
Clinical Safety Information
Clinical Decision Support — Not a Substitute for Clinical Judgment
Individual patient factors may require deviation from these recommendations.
Known Limitations
- Adults only. Children and adolescents: use the ATA 2015 paediatric guideline (ultrasound features, not size alone).
- Covers nodule work-up to cytology. Thyroid cancer treatment follows the ATA 2025 differentiated thyroid cancer guideline and is not covered.
- Molecular testing is summarised only; it is not Medicare-funded in Australia.
- Medullary, anaplastic cancer and lymphoma are not covered; red flags need urgent referral.
- Other ultrasound systems (EU-TIRADS, BTA U1-U5, K-TIRADS) use different cut-offs.
Contraindicated Populations
pediatric
Applicable Regions
USAUUKEU
AU: Radionuclide thyroid scans usually use Tc-99m pertechnetate. Molecular testing of thyroid FNA samples has no MBS item (MBS search Sep 2026).
UK: NICE NG12: consider a suspected cancer pathway referral for an unexplained thyroid lump. BTA 2014 uses U1-U5 ultrasound grading.
US: ATA 2015 patterns and ACR TI-RADS are both in use.
Version 2Next review: 2027-09-30
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Related Resources
Frequently Asked Questions
What is the Thyroid Nodule Evaluation (ATA 2015)?
The Thyroid Nodule Evaluation (ATA 2015) is a diagnostic clinical algorithm for Family Medicine. It provides a structured decision tree to guide clinical decision-making, based on 2015 ATA Management Guidelines for Adult Patients with Thyroid Nodules and Differentiated Thyroid Cancer (nodule sections); ACR TI-RADS 2017; Bethesda System 2023.
What guideline is the Thyroid Nodule Evaluation (ATA 2015) based on?
This algorithm is based on 2015 ATA Management Guidelines for Adult Patients with Thyroid Nodules and Differentiated Thyroid Cancer (nodule sections); ACR TI-RADS 2017; Bethesda System 2023 (DOI: 10.1089/thy.2015.0020).
What are the limitations of the Thyroid Nodule Evaluation (ATA 2015)?
Known limitations include: Adults only. Children and adolescents: use the ATA 2015 paediatric guideline (ultrasound features, not size alone).; Covers nodule work-up to cytology. Thyroid cancer treatment follows the ATA 2025 differentiated thyroid cancer guideline and is not covered.; Molecular testing is summarised only; it is not Medicare-funded in Australia.; Medullary, anaplastic cancer and lymphoma are not covered; red flags need urgent referral.; Other ultrasound systems (EU-TIRADS, BTA U1-U5, K-TIRADS) use different cut-offs.. Individual patient factors may require deviation from these recommendations.
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