Sodium Iodide (123 I) 37 MBq/ml

Hyperthyroidismis aendocrine diseasein which thethyroid glandproduces excessive amounts ofthyroid hormones.Thyrotoxicosisis a condition that occurs due to elevated levels of thyroid hormones of any cause and therefore includes hyperthyroidism.Some, however, use the terms interchangeably.Signs and symptoms vary between people and may include irritability, muscle weakness, sleeping problems, afast heartbeat,heat intolerance,diarrhea,enlargement of the thyroid, handtremor, andweight loss.Symptoms are typically less severe in the elderly and duringpregnancy.An uncommon but life-threatening complication isthyroid stormin which an event such as aninfectionresults in worsening symptoms such as confusion and ahigh temperature; this often results in death.The opposite ishypothyroidism, when the thyroid gland does not make enough thyroid hormone. Graves' diseaseis the cause of about 50% to 80% of the cases of hyperthyroidism in the United States.Other causes includemultinodular goiter,toxic adenoma,inflammation of the thyroid, eating too muchiodine, and too muchsynthetic thyroid hormone.A less common cause is apituitary adenoma.The diagnosis may be suspected based on signs and symptoms and then confirmed with blood tests.Typically blood tests show a lowthyroid stimulating hormone(TSH) and raisedT3orT4.Radioiodineuptake by the thyroid,thyroid scan, and measurement ofantithyroid autoantibodies(thyroidal thyrotropin receptor antibodies are positive in Graves' disease) may help determine the cause. Treatment depends partly on the cause and severity of the disease.There are three main treatment options:radioiodine therapy, medications, and thyroid surgery.Radioiodine therapy involves takingiodine-131by mouth, which is then concentrated in and destroys the thyroid over weeks to months.The resulting hypothyroidism is treated with synthetic thyroid hormone.Medications such asbeta blockersmay control the symptoms, andanti-thyroid medicationssuch asmethimazolemay temporarily help people while other treatments are having an effect.Surgery to remove the thyroid is another option.This may be used in those with very large thyroids or when cancer is a concern.In the United States, hyperthyroidism affects about 1.2% of the population.Worldwide, hyperthyroidism affects 2.5% of adults.It occurs between two and ten times more often in women.Onset is commonly between 20 and 50 years of age.Overall, the disease is more common in those over the age of 60 years.