Fast Five Quiz: Levothyroxine

Mary L. Windle, PharmD


October 07, 2021

Levothyroxine toxicity is uncommon and is most likely due to accidental ingestion. The onset of signs and symptoms may be delayed 3-10 days, owing to the time of T4 to be metabolized to the more active T3. Symptoms may include nervousness, insomnia, tremor, tachycardia, body temperature elevation, and loose stools. Serious effects are rare and include coma, convulsions, and acute psychosis. A one-time dose of as much as 3 mg is unlikely to cause symptoms in children or adults. Serious symptoms are less commonly seen in children than in adults for the same dose ingested; however, children typically have higher mean plasma levels of T3 and T4.

A patient handout on levothyroxine can be printed here.

This Fast Five Quiz was excerpted and adapted from the Medscape Drugs & Diseases articles Hypothyroidism and levothyroxine.

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