Fine needle aspiration biopsy--a critical investigation in thyrotoxicosis.

Four hundred and fifty two patients having clinical features of thyrotoxicosis have been studied for their hormonal (T4, T3 and TSH) content, I131 uptake levels and FNAB at repeated intervals. Four hundred and twenty seven had presented with diffuse enlargement and rest 25 cases with nodular enlargements. Of the primary hyperthyroidism cases 342 (82.4%) were of Grave's disease without exophthalmos and 73 (17.6%) with exophthalmos. T4, T3 and I131 uptake levels have correlated well with the degree of morphological changes as observed on FNAB. Degree of nuclear pleomorphism has correlated well with the duration of disease. Critical evaluation of morphological changes on FNAB has been done in all cases of primary hyperthyroidism being treated with neomercazole and radioactive iodine therapy. Treatment with neomercazole had shown, good correlation between time lag and the retrogressive changes. This was not so in cases treated with radioactive iodine therapy. Various known complications of radioactive treatment e.g. development of hypothyroidism, refractory and recurrent hyperthyroidism, exacerbation of the disease, radiation thyroiditis, and severe degree of dysplastic changes could be demonstrated in some cases on serial aspirations.