Fine needle aspiration in studies of thyroglobulin (Tg). Iodothyronine and iodine contents of Tg from patients with multinodular euthyroid goitre

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Abstract
Fine needle aspiration from the thyroid gland was performed in 10 patients with multinodular euthyroid goitre. This was done to evaluate the possibility of obtaining sufficient quantities of thyroglobulin by this procedure to allow biochemical characterization. For comparison aspiration from normal thyroid tissue was performed in seven subjects during operation for solitary thyroid lesions (cancer or cysts). The total amount of Tg in aspirate was, goitre 666 ± 171 μg (mean ± SE), normal 177 ± 52 μg; purified Tg contained, goitre vs. normal: iodine 9.1±2.2 vs. 26 ± 3.9; T4 0.86±0.39 vs. 4.0±0.7; T3 0.080±0.024 vs. 0.28±0.06 mol/mol Tg (all significantly different), compatible with iodine deficiency pattern in Tg from the patients with goitre. Similar values were obtained if iodine and iodothyronines were measured in crude aspirate (after alkaline ashing and pronase hydrolysis, respectively) and related to the amount of Tg in aspirate measured by radioimmunoassay; thus avoiding the cumbersome purification of Tg. Hence fine needle aspiration of the thyroid can be used to obtain Tg for biochemical analyses. This considerably facilitates Tg studies in humans for clinical or investigative purposes.