What is the role of the thyroid function tests in the evaluation of a solitary thyroid nodule?

Updated: Oct 04, 2018
  • Author: Daniel J Kelley, MD; Chief Editor: Arlen D Meyers, MD, MBA  more...
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Answer

Thyroid function tests should be obtained as part of the initial evaluation of solitary thyroid nodule, and findings are usually normal in patients with thyroid cancer. Metabolic evidence of hyperthyroidism is more commonly associated with benign disorders such as an autonomously functioning adenoma or Hashimoto thyroiditis. A strong association exists between Hashimoto thyroiditis and primary thyroid lymphoma.

The measurement of serum thyroglobulin levels has historically not been recommended in the evaluation of solitary thyroid nodule because it is also elevated in benign thyroid disorders. There is more recent data to suggest that elevated serum thyroglobulin, thyroglobulin antibody, and thyroid-stimulating hormone (TSH) levels may be associated with a higher risk of malignancy. Serum calcitonin and carcinoembryonic antigen (CEA) levels are usually elevated in patients with medullary thyroid carcinoma. However, serum CEA level has low specificity in the initial diagnosis of medullary thyroid carcinoma.

A retrospective study by Chami et al indicated that the measurement of serum TSH levels is not an effective means of screening for autonomously functioning thyroid nodules (AFTNs). The study involved 217 patients who had been diagnosed with an AFTN via thyroid scanning, in whom no thyroid nodules other than the AFTN were larger than 10 mm. The investigators found that TSH levels were normal in 49% of these patients and in 71% of the study’s patients who underwent a scan during workup of the thyroid nodule. [4]


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