Is there a hyperthyroid treatment for people with iodine allergy?

Conditions Expert Dr. Otis Brawley Chief Medical Officer,
American Cancer Society

Expert answer

Dear Tara: The thyroid is a gland in the front of the neck. It secretes a hormone that controls metabolism. People who have hyperthyroidism have a thyroid that is secreting too much hormone. Graves' disease is the most common form of hyperthyroidism.

When less severe, there is weight loss, the voice can be higher pitched and hair can be thin. For more severe hyperthyroidism, the heart rate is accelerated, there can be heart palpitations, shakiness, heat intolerance, sweating and shortness of breath. Some patients have swelling of the legs.

Initial treatment often involves the use of drugs called beta blockers to decrease symptoms. Secondary treatment is aimed at decreasing thyroid hormone secretion. In mild disease this can be done over a period of weeks with the administration of a thionamide drug (methimazole or propylthiouracil). An alternative is administration of radioactive iodine, which goes to the thyroid and obliterates it rather quickly. These are drugs that contain iodine.

Allergy to iodine and thionamide drugs is rare. Most people who have an iodine allergy have an allergy to iodine-containing proteins in shellfish and not to iodine itself or iodine-containing drugs. Hyperthyroid patients who have a true reaction to a drug are candidates for surgical removal of the thyroid.

Whatever treatment is used, initial monitoring should consist of periodic clinical assessments and measurements of thyroid levels in the blood. People rendered hypothyroid by treatment must have thyroid replacement therapy to survive.

Patients who have no thyroid hormone production because of surgery, radiation or certain diseases, and patients with low thyroid function because of immunologic diseases, have a condition known as hypothyroidism. Mild hypothyroidism involves weight gain, hair getting coarser, the voice getting deeper. In severe disease, the patient can develop dementia and even become comatose. A person with hypothyroidism must be treated with thyroid hormone replacement in order to live. Levothyroxine (brand name Synthroid) is the most common drug used as thyroid replacement. Patients who have a bad reaction to levothyroxine may be put on other hormone replacement drugs such as liothyronine or liotrix. In severe cases of a reaction, pork thyroid extract is generally well tolerated. These drugs must be titrated to the individual patient.

Thyroid disease also results in a negative calcium balance, leading to osteoporosis (reduced bone density) and increased fracture risk. Most patients with hyper- or hypothyroid disease should take 1,200 to 1,500 mg of elemental calcium daily.