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      Acute Effects of Clonidine and Growth-Hormone-Releasing Hormone on Growth Hormone Secretion in Patients with Hyperthyroidism

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          Abstract

          Patients with hyperthyroidism have reduced growth hormone (GH) responses to pharmacological stimuli and reduced spontaneous nocturnal GH secretion. The stimulatory effect of clonidine on GH secretion has been suggested to depend on an enhancement of hypothalamic GH-releasing hormone (GHRH) release. The aim of our study was to evaluate the effects of clonidine and GHRH on GH secretion in patients with hyperthyroidism. Eight hyperthyroid females with recent diagnosis of Graves’ disease (age range 20–55 years, body mass index range 19.2–26.2 kg/m<sup>2</sup>) and 6 healthy female volunteers (age range 22–35 years, body mass index range 19–25 kg/m<sup>2</sup>) underwent two experimental trials at no less than 7-day intervals: (a) an intravenous infusion of clonidine 150 µg in 10 ml of saline, or (b) a bolus intravenous injection of human GHRH (1–29)NH<sub>2</sub>, 100 µg in 1 ml of saline. Hyperthyroid patients showed blunted GH peaks after clonidine (7.1 ± 1.7 µg/l) as compared to normal subjects receiving clonidine (28.5 ± 4.9 µg/l, p < 0.05). GH peaks after GHRH were also significantly lower in hyperthyroid subjects (8.0 ± 1.7 µg/l) as compared to normal subjects receiving GHRH (27.5 ± 4.4 µg/l, p < 0.05). No significant differences in the GH values either after clonidine or GHRH were observed in the two groups of subjects examined. Our data demonstrate that the GH responses to clonidine as well as to GHRH in patients with hyperthyroidism are inhibited in a similar fashion with respect to normal subjects. That clonidine is not able to reverse the blunted GH secretion in hyperthyroidism suggests that hyperthyroxinemia may either cause an increase in somatostatin release by the hypothalamus or block GH secretion acting directly at the pituitary level.

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          Author and article information

          Journal
          HRE
          Horm Res Paediatr
          10.1159/issn.1663-2818
          Hormone Research in Paediatrics
          S. Karger AG
          1663-2818
          1663-2826
          1991
          1991
          02 December 2008
          : 36
          : 5-6
          : 192-195
          Affiliations
          aCattedra di Clinica Medica, University of Brescia, Italy; bDepartment of Health Sciences, University of Wisconsin, Milwaukee, Wisc, USA
          Article
          182159 Horm Res 1991;36:192–195
          10.1159/000182159
          1823078
          © 1991 S. Karger AG, Basel

          Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher. Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug. Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.

          Page count
          Pages: 4
          Categories
          Original Paper

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