Interleukin-1 receptor blockade does not affect endotoxin-induced changes in plasma thyroid hormone and thyrotropin concentrations in man

T. van der Poll, K. J. van Zee, E. Endert, S. M. Coyle, D. M. Stiles, J. P. Pribble, M. A. Catalano, L. L. Moldawer, S. F. Lowry

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Interleukin-1 (IL-1) has been implicated as a mediator of the euthyroid sick syndrome. The effects of IL-1 can be blocked by the naturally occurring IL-1 receptor antagonist (IL-1ra). In the present study, iv administration of endotoxin was used as a human model of the euthyroid sick syndrome. To assess the role of endogenous IL-1 in endotoxin-induced changes in plasma thyroid hormone and TSH concentrations, 18 healthy postabsorptive humans were studied on a control study day, followed 3 days later by a study day on which they were randomly assigned to one of three treatments: a 6-h infusion of recombinant human IL-1ra alone (133 mg/h), endotoxin alone (lot EC-5; 20 U/kg), or both endotoxin and IL-1ra. Administration of IL-1ra alone did not affect the plasma concentrations of thyroid hormones or TSH compared with those on the control day. Endotoxin injection was associated with decreases in T4 (P = 0.06 vs. the control day), free T4 (P = 0.02), T3 (P <0.001), and TSH (P <0.0001) and a rise in rT3 (P <0.001), reproducing the major features of the euthyroid sick syndrome. Coinfusion of IL-1ra did not influence these endotoxin-induced changes. Our results suggest that endogenous IL-1 does not play an important role in the alterations in plasma thyroid hormone and TSH concentrations induced by mild endotoxemia in healthy humans
Original languageEnglish
Pages (from-to)1341-1346
JournalJournal of Clinical Endocrinology and Metabolism
Issue number4
Publication statusPublished - 1995

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