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

J. Golstein; L. Vanhaelst; M. Camus; D. Glinoer

doi:10.1055/s-0028-1093667

Hormone and Metabolic Research, Table of Contents

Horm Metab Res 1976; 8(2): 128-131
DOI: 10.1055/s-0028-1093667

Originals

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

Abstract

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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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