If a circumscribed increased uptake is found in the scintigraphy, it indicates an autonomous adenoma. An autonomous adenoma is considered decompensated if only the circumscribed nodule is visible and the rest of the thyroid tissue is not.

 In this case, the metabolic state is often hyperthyroid, meaning TSH is suppressed and fT3 and fT4 are elevated. Occasionally, the metabolic state may still be euthyroid. Scintigraphy helps determine if significant autonomy is present. If the technetium uptake is over 1.5%, significant autonomy is present and should be treated. The treatment of an autonomous adenoma can be surgical or with radioiodine therapy. If only hot nodules are present in the thyroid, radioiodine therapy can be performed. If there are additional nodules (>1 cm), surgery is preferable. Radioiodine therapy only addresses the hyperfunction of the hot nodule. Other nodules may continue to grow and cause problems, even if they are classified as benign on ultrasound. Medications that suppress the body’s production of thyroid hormones (antithyroid drugs) are only used until the surgical therapy is performed for an autonomous adenoma. Long-term therapy of the autonomous adenoma with antithyroid drugs is generally only conducted in exceptional cases. Long-term treatment with antithyroid drugs has the disadvantages of enlarging the nodule and the overall thyroid volume and can cause side effects.