Management of Small Thyroid Nodules

Initial Assessment and Surveillance

The American Thyroid Association recommends performing a repeat ultrasound examination to reassess the nodule's size, characteristics, and risk stratification, followed by ultrasound-guided fine-needle aspiration if the nodule has grown to ≥1 cm or demonstrates suspicious sonographic features 1, 2
Nodules <1 cm at initial presentation have low clinical significance, but serial monitoring is essential because a subset may grow or develop high-risk features over time, as suggested by the American College of Endocrinology 1, 3

The American College of Radiology recommends that FNA is indicated only if suspicious features are now present, including marked hypoechogenicity, microcalcifications, irregular/microlobulated margins, absence of peripheral halo, solid composition, or central hypervascularity 3, 2
Surveillance without FNA is appropriate if the nodule remains <1 cm without suspicious sonographic features and no concerning clinical factors, as recommended by the American Thyroid Association 1, 2

Proceed directly to ultrasound-guided FNA regardless of sonographic appearance if the nodule has grown to ≥1 cm, as this size threshold mandates tissue diagnosis per multiple guideline recommendations, including those from the National Comprehensive Cancer Network 3, 2, 4
Measure serum TSH before FNA to assess functional status, though thyroid function tests have limited value for malignancy assessment since most thyroid cancers present with normal thyroid function, as noted by the Endocrine Society 3, 4

Do not rely on palpation alone to assess interval change, as ultrasound is far more sensitive for detecting growth in small nodules, according to the American Institute of Ultrasound in Medicine 1, 3, 2
Do not perform FNA on nodules <1 cm without high-risk features, as this leads to overdiagnosis and overtreatment of clinically insignificant papillary microcarcinomas (<1 cm) that carry excellent long-term prognosis, as recommended by the American Thyroid Association 1, 3, 2
Consider measuring serum calcitonin as part of the evaluation to screen for medullary thyroid cancer (5-7% of thyroid cancers), which has higher sensitivity than FNA alone for this specific malignancy, as suggested by the European Thyroid Association 3, 4