Overview
Thyroid Nodule
1. Clinical Overview
Summary
Thyroid nodules are common (palpable in 5%, incidental on imaging in 50%+). Most are benign (adenomas, cysts, colloid nodules). Key is to identify malignant nodules requiring surgery. Evaluation includes TFTs, thyroid ultrasound with U-classification (U1-U5), and FNA biopsy for suspicious nodules. Management is based on cytology (Thy1-5) and ultrasound features.
Key Facts
- Prevalence: 50% of adults have nodules on ultrasound
- Malignancy rate: 5-10% of nodules
- Investigations: TFTs, USS (U-classification), FNA if U3-U5
2. U Classification (Ultrasound)
| Grade | Features | FNA |
|---|---|---|
| U1 | Normal | No |
| U2 | Benign | No |
| U3 | Indeterminate | Consider |
| U4 | Suspicious | Yes |
| U5 | Malignant | Yes |
3. Thy Classification (Cytology)
| Grade | Interpretation | Action |
|---|---|---|
| Thy1 | Non-diagnostic | Repeat FNA |
| Thy2 | Benign | Follow-up |
| Thy3a | Atypia | Repeat/surgery |
| Thy3f | Follicular | Consider surgery |
| Thy4 | Suspicious | Surgery |
| Thy5 | Malignant | Surgery |
4. References
- BTA Guidelines for Thyroid Nodules. 2014.
Last Reviewed: 2026-01-01 | MedVellum Editorial Team