Thyroid Nodules
Thyroid nodules are lumps that form within the thyroid gland. They are extremely common — most adults have at least one detectable by ultrasound — and the great majority are benign.
The goal of evaluation is to identify the small minority that are or could become cancerous, or that produce excess hormone.
Last medically reviewed: 1 November 2025
Key points
- Most thyroid nodules are benign.
- Ultrasound assesses risk; biopsy is used for suspicious nodules.
- Small low-risk nodules are often monitored.
- A rapidly growing nodule or new voice change needs prompt review.
What causes nodules?
Most nodules are colloid nodules — overgrowths of normal thyroid tissue — or benign adenomas. Iodine deficiency, thyroiditis, and genetic factors contribute. Only a small percentage are malignant.
Risk factors for cancer include a history of neck radiation in childhood, a family history of thyroid cancer, certain genetic syndromes, and age over 60 or under 20 at presentation.
How are nodules evaluated?
Evaluation starts with TSH testing — a suppressed TSH may indicate a hormone-producing (toxic) nodule. Ultrasound characterises size, composition (solid, cystic, mixed) and suspicious features such as microcalcifications or irregular margins.
Fine needle aspiration cytology (FNAC/FNA) samples cells from nodules meeting size and ultrasound-risk criteria. Results are reported on a standardised scale (Bethesda classification) from benign to suspicious.
What happens after evaluation?
Benign-appearing nodules are typically monitored with periodic ultrasound rather than removed. Suspicious or cancerous nodules may require diagnostic surgery (lobectomy or total thyroidectomy). Toxic nodules causing hyperthyroidism are treated with antithyroid drugs, RAI or surgery.
Large benign nodules causing compressive symptoms — difficulty swallowing or breathing — may also be removed.
Frequently asked questions
Do all thyroid nodules need a biopsy?
No. FNAC is recommended only for nodules meeting specific size and ultrasound-risk criteria. Most small, benign-appearing nodules are followed with ultrasound surveillance.
Can nodules turn into cancer later?
Benign nodules rarely transform into cancer. The main risk is missing a cancer at initial evaluation, which is why ultrasound risk stratification and appropriate FNAC matter.
Should I worry if I can feel a lump?
Many palpable nodules are benign, but any new neck lump should be evaluated — ultrasound is a simple, non-invasive first step.
References & further reading
This page is based on established medical knowledge and guidelines from authoritative sources. Always consult a qualified clinician for personal medical advice.
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