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      Does a Positive Oestrogen Feedback on the Hypothalamic-Pituitary Axis Exist Concurrently with a Defective Testosterone Feedback in Klinefelter’s Syndrome?

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          Abstract

          The oestrogen provocation and GnRH challenge tests were carried out in 5 subjects with Klinefelter’s syndrome who had no history of previous hormonal therapy. The oestrogen provocation test consisted of an intramuscular injection of 10 mg of oestradiol valerate and blood samples were collected daily from day 0 to day 5. In 2 subjects, three GnRH challenge tests were carried out before (day 0) and on days 2 and 4 after the intramuscular injection of oestradiol valerate. During each GnRH challenge test, 7 blood samples were collected at 30-min intervals, 30 min and immediately before and for 150 min after the bolus dose of GnRH. Plasma concentrations of FSH, LH, testosterone and oestradiol were measured by established radioimmunoassays. Plasma levels of oestradiol rose significantly a day following the intramuscular injection of 10 mg of oestradiol valerate, reaching a peak on day 2 and then falling significantly to lower levels by days 4 and 5, although these levels were still significantly higher than the corresponding baseline levels. In the presence of high levels of oestradiol, the high basal levels of FSH were significantly suppressed, and remained suppressed throughout the 5 days of the study. LH, on the other hand, had a biphasic response; an initial significant suppression by day 1 persisting to day 3, but by days 4 and 5 a rebound in basal LH levels was noted. However, the levels on day 5 were not significantly higher than baseline levels. The pituitary responsiveness as far as the LH and FSH secretions were concerned reflected the baseline levels. The results of the present study refuted the claim that a positive oestrogen feedback exists in men including Klinefelter’s syndrome as a result of the removal of or reduced testosterone. In addition, the attenuated testosterone feedback in Klinefelter’s syndrome is responsible for the greatly amplified pituitary responsiveness to the trophic action of GnRH and this, in part, may be responsible for the elevated levels of FSH and LH seen in such patients.

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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
          1998
          September 1998
          08 October 1998
          : 50
          : 3
          : 160-165
          Affiliations
          Departments of a Obstetrics and Gynaecology and b Medicine, National University of Singapore, National University Hospital, Singapore
          Article
          23266 Horm Res 1998;50:160–165
          10.1159/000023266
          9762005
          © 1998 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
          Figures: 2, Tables: 1, References: 23, Pages: 6
          Categories
          Original Paper

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