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Horm Metab Res 1976; 8(2): 128-131
DOI: 10.1055/s-0028-1093667
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© Georg Thieme Verlag KG Stuttgart · New York

Paradoxical Modulation of Thyrotrope Responsiveness to TRH during the Treatment of Thyrotoxic Patients: Apparent Absence of Feed-Back Regulation

J.  Golstein1 , L.  Vanhaelst2 , M.  Camus3 , D.  Glinoer3
  • 1Institut de Recherche Interdisciplinaire (LMN), Universities of Brussels, Belgium
  • 2Laboratorium voor Experimentele Genesskunde, Universities of Brussels, Belgium
  • 3Department of Radioisotopes, Hopital Saint-Pierre, Universities of Brussels, Belgium
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Publication History

Publication Date:
23 December 2008 (online)

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Abstract

Eight patients with active thyrotoxicosis have been followed up to one year after the onset of antithyroid treatment. At different time intervals during the investigation period, TRH tests were performed and total T4 and T3 basal levels were measured. The TRH-induced TSH release was delayed in all patients in spite of a normalization of the circulating levels of thyroid hormones. The delay varied according to the patients and lasted, in some cases, for as long as 24 weeks after the normalization of the thyroid hormone levels. Administration of thyroid hormones, together with methimazole, did not seem to prevent the pituitary thyrotropes responsiveness; moreover, it did not provoke an inhibition of the TRH induced TSH release once the thyrotropes reactivity was fully restored. The feed-back mechanism does not seem to be the main modulator of the pituitary responsiveness to TRH in these circumstances.

Key words

Thyrotoxicosis - TRH Test - Antithyroid Drugs - Thyroid-Pituitary Feed-Back

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