In one case, hyperthyroidism is possible and the thyroid scan shows a hot nodule (concentrated radioisotope distribution), which is called a toxic thyroid adenoma; in the other case, the thyroid scan shows a warm nodule (radioisotope distribution similar to normal thyroid tissue) or a cold nodule (radioisotope distribution lower than normal thyroid tissue), which is not called a toxic thyroid adenoma. thyroid adenoma, but a simple thyroid adenoma. Toxic thyroid adenoma is a manifestation of hyperthyroidism due to the increased function of the adenoma and the production of large amounts of thyroid hormones. Toxic thyroid adenomas are most often seen in women, mostly between the ages of 30 and 40. The adenoma is usually a single one, with a few more than one. Patients have symptoms of hyperthyroidism, and examination often reveals nodules in the thyroid gland, which are usually large, often up to several centimeters in size. Serum T3 and T4 levels are measured to be elevated, with T3 elevation being the most obvious. A thyroid scan confirms that the nodules are hot nodules, but the surrounding thyroid tissue is often lacking or hypoactive in radioisotope distribution.