What is a thyroid nodule?
A thyroid nodule is a lump that forms inside the thyroid gland at the front of the neck. Few can be felt, but high-resolution ultrasound finds them in about 20–68% of adults, and the vast majority are benign (Durante et al., 2018).
This article is general health information and is not a substitute for diagnosis or treatment. If symptoms persist, see a doctor.
Which nodules need a biopsy?
Evaluation starts with a TSH blood test and an ultrasound to classify risk. American Thyroid Association guidelines combine the ultrasound pattern with size to decide on fine-needle aspiration (FNA) (Haugen et al., 2016).
| Ultrasound pattern | Example features | FNA cutoff (largest size) |
|---|---|---|
| High suspicion | Solid hypoechoic, irregular margins, microcalcifications, taller-than-wide | 1 cm or more |
| Intermediate | Solid hypoechoic, smooth margins | 1 cm or more |
| Low | Iso- or hyperechoic solid, partly cystic | 1.5 cm or more |
| Very low | Spongiform, partly cystic without suspicious features | 2 cm or more, or observe |
| Benign | Pure cyst | Not needed |
Voice changes, trouble swallowing, a rapidly growing lump or enlarged neck lymph nodes call for faster evaluation.
What is the thyroid cancer overdiagnosis debate?
After thyroid ultrasound became a routine part of health checkups in South Korea, thyroid cancer diagnoses rose about 15-fold between 1993 and 2011, while thyroid cancer deaths barely changed. Researchers concluded that most of the increase was overdiagnosis—finding small cancers that would never have caused harm (Ahn, Kim & Welch, 2014). Today, screening ultrasounds aren't recommended for people without symptoms, and small low-risk nodules are often just monitored. To put risk numbers in context, see relative vs. absolute risk.
FAQ
- Do thyroid nodules need surgery?
- Most are benign and are followed with periodic ultrasound. Surgery or ablation is considered if a biopsy suggests cancer or a large nodule causes pressure symptoms.
- Can a nodule affect thyroid function?
- Most don't, but some produce excess hormone and cause hyperthyroidism, which is why TSH is checked.
Sources reviewed: 2026-10-25
References
- Haugen, B. R., Alexander, E. K., Bible, K. C., et al. (2016). 2015 American Thyroid Association management guidelines for adult patients with thyroid nodules and differentiated thyroid cancer. Thyroid, 26(1), 1–133.
- Durante, C., Grani, G., Lamartina, L., Filetti, S., Mandel, S. J., & Cooper, D. S. (2018). The diagnosis and management of thyroid nodules: A review. JAMA, 319(9), 914–924.
- Ahn, H. S., Kim, H. J., & Welch, H. G. (2014). Korea's thyroid-cancer "epidemic"—screening and overdiagnosis. New England Journal of Medicine, 371(19), 1765–1767.