Acute beta-blockade changes the extracellular distribution of thyroid hormones.


The acute (within hours) changes in the concentrations of T4, T3, reverse-T3 (rT3) and T3 resin uptake test (T3RU) were studied in 31 hyperthyroid patients for 4 h after po treatment with either acebutolol, oxprenolol, pindolol or timolol. In 21 of the patients, the changes were compared to changes in the serum concentrations of alpha 2-macroglobulin (a macromolecule) and two middle-sized molecules; thyroid hormone-binding globulin (TBG) and albumin in order to calculate the changes in extracellular distribution of the thyroid hormones and to distinguish between changes due to a changed metabolism and changes due to a changed distribution of the thyroid hormones. Acebutolol, oxprenolol and timolol caused a decrease in serum T3 after 1/2 h, and acebutolol and oxprenolol also a decrease in rT3 after 1/2 - 1 h, the changes reversed within 2 h. A concomitant decrease in serum albumin and TBG suggests a change in the extracellular distribution of middle-sized molecules to which thyroid hormones are attached, as an explanation of the acute decrease (1 h) of the thyroid hormones. The small and insignificant change in alpha 2-macroglobulin indicates that the changes are mainly extravascular, but the difference of alpha 2-macroglobulin changes between the drugs (acebutolol/timolol vs pindolol/oxprenolol) could depend on the intrinsic sympathomimetic activity of the drugs.

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@article{Kayser1990AcuteBC, title={Acute beta-blockade changes the extracellular distribution of thyroid hormones.}, author={Lars Kayser and Hans Perrild and Per Hyltoft Petersen and L. Skovsted and James E. Hansen}, journal={Journal of endocrinological investigation}, year={1990}, volume={13 4}, pages={277-81} }