The Yield of Adequate and Conclusive Fine-Needle Aspiration Results in Thyroid Nodules is Uniform Across Functional and Goiter Types

Relatively little is known about the cytological characteristics of hyperfunctioning (hot) thyroid nodules. Concern has been expressed that fine-needle aspiration (FNA) identifies hot nodules as follicular tumors or indeterminate, and as a consequence patients could be unnecessarily referred for surgery. Between 1979 and 1996, thyroid FNA was performed on 829 patients. Result of thyroid scan was available in 326; 69 (21%) patients had hot, and 257 (79%) had warm or cold thyroid nodules. Nodules in each of these major groups were divided into 2 subgroups: clinically solitary nodules and dominant nodules in multinodular goiters (MNG). The frequencies of adequate versus inadequate FNA samples, and of conclusive versus indeterminate FNA results were determined separately for each of the groups and subgroups. In addition, patients with hot nodules and overt hyperthyroidism were identified and evaluated separately. Bivariate analyses were performed for the frequency of adequate versus inadequate smears and conclusive versus indeterminate results between hot, toxic, and cold-warm nodules, and between solitary nodules and MNG. The frequency of adequate aspirations and conclusive results in the various groups and subgroups was found to be statistically indistinguishable. In conclusion, the yield of adequate samples and the rate of conclusive results of FNA in thyroid nodules is similar, irrespective of the functional state or of goiter presentation. Hot thyroid nodules do not seem to produce an increase in the rate of inadequate or indeterminate FNA results, and therefore, do not affect the overall performance of thyroid FNA.