Therapeutic options in the management of autonomously functioning thyroid adenomas

Full text: Autonomously functioning thyroid nodules or adenomas (AFTN or AFTA) was established as a clinical entity in 1918 by Goetsch correlating cellular mitochondrial content with nodular function and showing the inverse correlation between AFTN function and extra nodular tissue function. They are almost always benign and degeneration, which is common in AFTN, can result in the development of hyperthyroidism. It is therefore important to know the function of these nodules by requesting for the thyroid function tests namely T3, T4, and TSH. They are diagnosed by thyroid scans using I-131 or Tc 99m as a hot solitary nodule in one lobe with the other lobe not appearing on scan or suppressed. The frequency of AFTA worldwide is quite variable depending on geography. It ranges from 1% in North America to 10 % in some areas in Europe and Asia or in areas of iodine deficiency. The traditional methods of treatment of these nodules have been surgery and radioactive iodine ablation. Surgical treatment as a rule is indicated in young patients with nodules larger than 3 cm and those with local compressive symptoms. RAI is used in elderly patients and those who are poor surgical risks. The usual dose ranges from 20 to 30 mCi and is definitely larger that when treating Graves' disease. Others have resorted to PEI or percutaneous ethanol injection with reported success. There has been no definite management of these AFTA due to the variable natural history and some would only recommend observation for asymptomatic small adenomas, which are euthyroid. Therefore this paper studied the results of treatment using RAI ablation, surgery or plain observation for AFTA. Percutaneous ethanol injection is not being done in our center. In the local setting, where thyroid disease is still endemic, the incidence of AFTA is not so high. Graves' disease is still the predominating cause of hyperthyroidism followed by multinodular goiter. Toxic AFTA occurs in 3% of the total hyperthyroid patients. In a ten-year review of the course of the disease after treatment with any of the three modalities of surgery, RAI and purely observation, there still seem to be no common consensus, which the best treatment modality is. Forty-eight patients were included in the study. Among these patients were 43 females and 5 males. Majority were over fifty years old. Among the 48 patients, thirty-nine were toxic and 9 were non-toxic. Of the toxic patients, twelve patients underwent surgery of the affected lobe, undergoing lobectomy or nodulectomy, while 19 patients were given radioactive iodine with a dose range of 20 to 30 mCi. Eight patients just had antithyroid drugs and were just observed. Among the nine patients who were euthyroid, five were just observed but requiring periodic followup while four underwent surgery. Two of the total population, one hyperthyroid and one euthyroid patient while being observed after 6 months and three months respectively developed rapid growth of the nodules. FNAB was done which showed well differentiated CA (papillary and follicular) hence underwent total thyroidectomy or near total thyroidectomy, RAI ablation and lifetime thyroid hormone suppression. The results of the 3 modalities were compared and the best results were seen in the group given RAI in terms of cost effectiveness, diminished size of the nodules to disappearance of nodules and relief of symptoms. Hypothyroidism was not a problem as only two patients developed such. Those who were observed only still had the nodules, which became bigger in size with the antithyroids while the incidence of hypothyroidism secondary to surgery was higher in this study as seen in 4 patients. In conclusion, the three modes of treatment has its own weaknesses and strengths and treatment should be individualized depending on which age group the patient belongs (very important consideration) as well as patients choice, size of the nodule and function of the nodule. I-131 may still be the treatment of choice especially in the elderly since they have concomitant cardiac problems. However in the younger age group and for bigger nodules, surgery may be preferred for aesthetic reasons and since they are good surgical risks. Pure antithyroid treatment usually is not recommended. (author)