LT4

Medical abbreviation · Drug

LT4 stands for Levothyroxine, a drug abbreviation.

Synthetic form of thyroxine (T4), the standard treatment for hypothyroidism and one of the most prescribed drugs in the US. Doses are adjusted in small steps based on TSH blood tests.

Example: LT4 75 mcg daily, 30-60 minutes before breakfast; TSH in 6-8 weeks.

Usage notes

Absorption is reduced by food, coffee, calcium, iron and proton pump inhibitors, so it is taken on an empty stomach and separated from those products by about four hours. Levothyroxine is a narrow therapeutic index drug, so brand or manufacturer switches often prompt a TSH recheck. Sold as Synthroid, Levoxyl, Tirosint and Euthyrox.

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This entry is for general education and is not medical advice. Abbreviation use varies between institutions; always confirm in context.