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ISMP Canada News

March 8, 2017: Express Levothyroxine Doses in Micrograms not Milligrams

Multiple cases of errors and near misses involving levothyroxine dose conversions from milligrams (mg) to micrograms (mcg) and vice versa have been reported to ISMP Canada and in the literature. Canadian manufacturer labels express levothyroxine doses in micrograms (mcg) only. However, throughout the medication-use process (e.g., prescribing, dispensing, and administration), levothyroxine doses may be expressed in micrograms (mcg) or in milligrams (mg). As a result, patients and healthcare providers may need to convert doses from milligrams (mg) to micrograms (mcg), or vice versa, to match the prescribed dose to a particular product. Errors in the calculations required to convert between units are contributing to these errors and near misses.  Read more ...