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International Journal of Endocrinology
Volume 2010, Article ID 370692, 4 pages
http://dx.doi.org/10.1155/2010/370692
Case Report

Spuriously Elevated Serum IGF-1 in Adult Individuals with Delayed Puberty: A Diagnostic Pitfall

1Division of Endocrinology & Metabolism, Dalhousie University, Halifax, NS, Canada B3H 3J5
2Divisions of Endocrinology & Metabolism & Neurosurgery, Halifax Neuropituitary Program, 7th Floor N, VG Site, 1278 Tower Road, Halifax, NS, Canada B3H 2Y9
3Division of Endocrinology, The University of Manchester, Manchester M13 9PL, UK
4Division of Endocrinology, University of Toronto, Toronto, ON, Canada M5S 1A1

Received 25 May 2010; Revised 9 June 2010; Accepted 9 August 2010

Academic Editor: Ariel L. Barkan

Copyright © 2010 Syed Ali Imran et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Serum insulin-like growth factor-1 (IGF-1) is a sensitive marker of growth hormone (GH) activity. The levels of IGF-1 vary widely, peaking during puberty and declining with advancing age. During adolescence, serum IGF-1 levels tend to correlate better with pubertal stage rather than chronological age. Here we discuss two cases of delayed puberty, both in their 20s, who presented with high serum IGF-1 but no clinical or biochemical evidence of hypersomatotropism as confirmed by appropriate GH response to an oral glucose challenge. Both individuals achieved full pubertal status with testosterone replacement therapy and their serum IGF-1 levels settled into normal age-specific range. We suggest that in chronologically adult individuals with delayed puberty, serum IGF-1 should not be interpreted on the basis of age-specific normal values but rather on their pubertal status. Furthermore, in the absence of another cause of elevated IGF-1, the expectation is that IGF-1 levels will decline towards age-normative ranges following androgen replacement therapy.