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Thyroid Problems (cont.)

Medications for hyperthyroidism

Beta-blockers: This class of medications works by blocking many of the body's responses to hyperthyroidism. It decreases tremor, nervousness, and agitation. It also reduces the fast heart rate. It is given as tablets to the person with mild to moderate symptoms, and as an IV preparation to the person with the severe form of hyperthyroidism (thyrotoxic crisis).

Propylthiouracil: This antithyroid drug works by blocking thyroid hormone synthesis. It takes several months after starting the medication for the full therapeutic effect to be achieved. Common mild side effects include an itchy rash. More rare, serious side effects include a decrease in white blood cell count, which can decrease the ability to fight off infection. Therefore, a high fever should prompt a call to the doctor. This medication can rarely cause liver dysfunction.

Methimazole (Tapazole): This antithyroid drug also works by blocking thyroid hormone synthesis. It may take slightly longer than propylthiouracil to achieve its full effect. It has similar side effects as propylthiouracil.

Iodide (Lugol's solution, Strong iodine): This medication works by inhibiting the release of thyroid hormone from the overfunctioning thyroid gland. It must be used in conjunction with an antithyroid drug because the iodine can be used to increase the amount of thyroid hormone and worsen the hyperthyroidism. Common side effects include nausea and a metallic taste in the mouth.

Medications for hypothyroidism

L-thyroxine (Synthroid, Levoxyl, Levothroid, Unithroid): This medication is the mainstay of thyroid hormone replacement therapy in hypothyroidism. This is a synthetic form of thyroxine. The body tissues convert it to the active product L-triiodothyronine. Side effects are rare, and it has an excellent safety record.

L-triiodothyronine: This is rarely used alone as thyroid hormone replacement, because it has less uniform potency than L-thyroxine. Its use can cause rapid increases in L-triiodothyronine concentration, which can be dangerous in the elderly and in people with cardiac disease. It may be used in combination with L-thyroxine for people who have poor symptomatic relief with L-thyroxine alone.
Thyroid extract: This is not recommended as a thyroid hormone replacement. There is an excess of T3 in this preparation, and the amount of thyroid hormones (T4, T3) is variable between batches.