Hyperthyroidism is a condition in which an excess of thyroid hormone (thyroxine) is produced from an overactive thyroid gland (or taking too much thyroid hormone).

The most common form of hyperthyroidism is called Graves' disease. The second form is a multinodular goiter (an enlarged thyroid). Hyperthyroidism with diffuse goiter is a condition due to an excessive functional activity of the thyroid gland. Hyperthyroidism and Graves' disease are considered to be synonymous. The most common cause of hyperthyroidism (overactive thyroid) is the overproduction of thyroid hormone by the entire thyroid gland. Graves' disease is caused by antibodies in the blood that turn on the thyroid and cause it to grow and secrete too much thyroid hormone. This can be genetic in families.

Manifestations of Graves' disease can be divided into two categories:

1. Those symptoms secondary to overstimulation of the sympathetic nervous system which include goiter, increased heart rate, nervousness, increased systolic blood pressure, fine hand tremor, and exophthalmus;

2. Those symptoms related to the direct effect of increased metabolism such as, weight loss, eating more food than required (hyperphagia), agitation, and delirium.

In addition, masked or apathetic hyperthyroidism as seen in the elderly will present without the classic symptoms. Instead, the elderly will manifest cardiovascular symptoms, weight loss or change in personality.

In hyperthyroidism, the thyroid-stimulating hormone (TSH) level is subnormal or suppressed. Testing for TSH confirms the diagnosis due to its sensitivity.

Initial treatment is to blunt the effects of thyroxine. The ultimate goal is to decrease thyroid hormone production through surgery, radioactive iodine (RAI), or medication depending on the patient's age and personal preference.

Approximately 20% of patients exhibit spontaneous remission and become hypothyroid (decreased release of thyroid hormone) in 20 to 30 years. Patients who are left untreated experience cardiac-related manifestations that may lead to stroke and ultimately death.

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

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