Thyroid Neoplasms

THYROID NEOPLASMS

Neoplasms of the thyroid gland may be benign (adenomas) or malignant. The primary diagnostic test is a fine needle aspiration biopsy and cytologic examination. Benign lesions may be moni-tored for growth or symptoms of local obstruction, which would mandate surgical excision. Levothyroxine therapy is not recom-mended for the suppression of benign nodules, especially in iodine sufficient areas. Management of thyroid carcinoma requires a total thyroidectomy, postoperative radioiodine therapy in selected instances, and lifetime replacement with levothyroxine. The evalu-ation for recurrence of some thyroid malignancies often involves withdrawal of thyroxine replacement for 4–6 weeks—accompanied by the development of hypothyroidism. Tumor recurrence is likely if there is a rise in serum thyroglobulin (ie, a tumor marker) or a positive ¹³¹I scan when TSH is elevated. Alternatively, administra-tion of recombinant human TSH (Thyrogen) can produce com-parable TSH elevations without discontinuing thyroxine and avoiding hypothyroidism. Recombinant human TSH is adminis-tered intramuscularly once daily for 2 days. A rise in serum thyro-globulin or a positive ¹³¹I scan will indicate a recurrence of the thyroid cancer.