Fast Five Quiz: Levothyroxine

Mary L. Windle, PharmD


October 07, 2021

Treatment decisions may be compromised by the use of medications that interfere with accurate thyroid function testing. A study of 170,261 patients taking levothyroxine found that around 28% were taking prednisone or prednisolone, 8% were taking amiodarone, and 1.42% were taking phenytoin. Other reported drugs that could potentially interfere included carbamazepine (0.91%), phenobarbital (0.15%), lithium (0.40%), and tamoxifen (0.11%).

Read more about drugs that interfere with thyroid-stimulating hormone (TSH) interpretation.


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