Thyroid enlargement, toxic (previously called thyroid gland, toxic adenoma of) refers to a toxic tumor of the thyroid gland that increases the formation and secretion of principal thyroid hormones T3 and T4. The nodule can be singular (if more than 2 to 3 cm in size), or there may be multiple nodules. This condition is more common in the elderly.

The patient has had a goiter for a long time before oversecretion of T3 and T4 begins. Excess iodine intake may precipitate this toxic state (Jod-Basedow disease).

Overstimulation may include enlarged thyroid, either a single 2 to 3 cm. nodule, or multinodular. The nodules may extend below the sternum. In the elderly, the condition may present with the signs and symptoms of apathetic hyperthyroidism, e.g. lack of emotion, depressed mood, weight loss, and cardiac symptoms. (See Diagnostic Code: 7900 Hyperthyroidism for signs and symptoms of hyperthyroidism.)

Laboratory values will evidence a suppressed level of thyroid-stimulating hormone (TSH) and visibly increased T3 levels. The T4 levels are only slightly increased, and the radioactive iodine (RAI) uptake shows either an irregular uptake or distinct hot nodules with RAI accumulation.

Radioactive iodine (RAI) is the preferred treatment in the United States; however, initial treatment involves the use of antithyroid medications. In addition, beta-blocking agents are instituted immediately to blunt the effects of elevated thyroxine levels on the heart, blood pressure and nervous system. Surgery may be done to remove adenomas in younger patients.

A permanent decrease in thyroid function rarely occurs once the toxic adenoma is destroyed.

• Consider service connection on a presumptive basis as a chronic condition (38 CFR §3.307; §3.309(a)).

• Consider service connection on a presumptive basis as a condition associated with ionizing radiation exposure (38 CFR §3.307; §3.309(d); §3.311).

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