BACKGROUND: Thyroid fine-needle biopsy (FNB) is a simple, reliable, inexpensive, and generally safe diagnostic procedure in the management of thyroid nodules. Local pain and minor hematomas are the most common clinical complications, and hemorrhage and fibrosis the most common histological alterations after thyroid FNB. FNB can also trigger biochemical alterations in serum, since it may destroy thyroid follicles. In this review we summarized the biochemical alterations in serum that occur after diagnostic thyroid FNB, aiming to review information that would be potentially useful in interpreting thyroid tests in patients who recently had a thyroid FNB.
SUMMARY: Computerized advanced search for primary evidence was performed in the PubMed (Public/Publisher MEDLINE) electronic database not limited by publication time and English language. An increase in serum thyroglobulin (Tg) ranging from 35% to 341% occurs in 33-88% of patients subjected to FNB. Serum Tg concentrations typically return to baseline about 2-3 weeks after FNB. The abrupt release of Tg after FNB may induce the production of autoantibodies to Tg and thyroid hormones in a minority of patients. There is little information on the effect of FNB on autoantibodies to thyroid peroxidase. No changes seem to occur in thyroid-stimulating hormone, total thyroxine, free thyroxine, free triiodothyronine (T3), or reverse T3, while controversy exists for T3.
CONCLUSIONS: The degree of increase in serum Tg after FNB is highly variable and not a predictor of whether the biopsied nodule is benign or malignant. The increase or development of Tg autoantibodies that occurs in some patients does not appear to be of clinical significance. Development of autoantibodies to thyroid hormones may be more likely in patients whose biopsied nodule is benign than malignant, but further studies are required to confirm this. If changes in serum thyroid-stimulating hormone or thyroid hormones are noted in a patient with a history of a recent fine-needle aspiration, they should be investigated since they are not likely to be related to the biopsy.