Which medications in the drug class Thyroid hormones are used in the treatment of Myxedema Coma or Crisis?

Updated: Aug 31, 2020
  • Author: Mohsen S Eledrisi, MD, FACP, FACE; Chief Editor: George T Griffing, MD  more...
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Thyroid hormones

Immediate administration of intravenous levothyroxine is advised if myxedema coma is suspected.

Levothyroxine (Synthroid, Levoxyl)

In active form, influences growth and maturation of tissues. Involved in normal growth, metabolism, and development. IV dosage form has a long half-life (may be administered qd and is the preferred route of administration in patients with myxedema coma/crisis because GI tract absorption may be compromised). Preferred by many authorities, because the onset of action is slow and sustained, making adverse effects less likely to occur and serum levels easier to monitor. Administering only T4 assumes normal conversion to T3 by deiodinase activity, which is usually compromised in severe illness. IV dose of T4 is approximately one half to two thirds of the PO dose. Lower doses recommended if patient has uncontrolled atrial arrhythmia or recent MI.

Liothyronine (Cytomel, Triostat)

Synthetic form of the natural thyroid hormone, T3, converted from T4. T3 is the active form, but because peripheral conversion of T4 to T3 is compromised in patients who are hypothyroid, some authorities suggest combined IV T4 and T3 in these patients. However, patients with cardiovascular disease are at greater risk of arrhythmia and infarction.

T3 has a short half-life and must be administered q8h. Because of concerns about abrupt onset and fluctuating concentrations in tissues, experts advise coadministration of T3 with T4.

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