Hypothyroidism Medication

Updated: Mar 16, 2017
  • Author: Philip R Orlander, MD; Chief Editor: George T Griffing, MD  more...
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Medication

Medication Summary

The goals of pharmacotherapy are to reduce morbidity and to prevent complications. Thyroid hormone is administered to supplement or replace endogenous production.

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Thyroid Products

Class Summary

Thyroid hormone influences growth and maturation of tissues. It is involved in normal growth, metabolism, and development. Levothyroxine (LT4) is generally considered to be the treatment of choice for patients with hypothyroidism.

Levothyroxine (Synthroid, Levoxyl, Levothroid, Unithroid, Tirosint)

Thyroid hormone influences growth and maturation of tissues. It is involved in normal growth, metabolism, and development. Levothyroxine (LT4) is generally considered to be the treatment of choice for patients with hypothyroidism.

Liothyronine (Cytomel, Triostat)

Liothyronine (LT3) is a synthetic form of the natural thyroid hormone (T3) converted from T4. It is not intended for use as sole maintenance therapy, but in rare cases it can be used together with LT4 in small doses (5-15 µg/day).The recommended ratio of T4 to T3 is 10-14:1. T3 has a short duration of activity (half-life, 12-24 hours), which allows quick dosage adjustments in the event of overdosage.

Theoretically, LT3 may be preferred when gastrointestinal (GI) absorption is impaired (95% of this hormone is absorbed, compared with 50-80% of T4) or if peripheral conversion is impaired. Dosage recommendations are for short-term use in special circumstances (eg, myxedema coma), under the guidance of an endocrinologist. Dosage should be determined in consultation with an endocrinologist.

Dosage recommendations are for short-term use in special circumstances (see above) with the guidance of an endocrinologist.

Thyroid desiccated (Armour Thyroid, Nature-Throid, Westhroid)

Desiccated thyroid is derived from extracts of bovine or porcine thyroid glands. Some manufacturers standardize their formulations on the basis of bioassays, whereas others use iodine content.

Desiccated thyroid is referred to as natural thyroid and generally contains T3 and T4 in a 1:4 ratio. It is made in a range of strengths, with tablets including 1/8, 1/4, 1/2, 1, 2, 3, 4, or 5 grains. One grain (60 mg) contains about 38 µg of T4 and 9 µg of T3. Because these preparations contain variable quantities of T3, they should not be prescribed for patients with known or suspected cardiac disease and are generally avoided. They also are not preferred in pregnancy, because they produce relatively lower T4 levels.

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