Growth hormone abuse in the horse: preliminary assessment of a mass spectrometric procedure for IGF‐1 identification and quantitation

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Abstract
Previous studies have shown that insulin‐like growth factor 1 (IGF‐1) is a promising marker for the detection of growth hormone (GH) abuse in the horse. The significant increases observed with GH administration in comparison to natural levels imply the possibility of setting a threshold level for IGF‐1 that would be indicative of GH abuse. Although an immunoradiometric assay (IRMA) has been identified as a reliable screening method, a more specific IGF‐1 quantification method needs to be developed for the prosecution of GH abuse by horseracing authorities. This study describes such an HPLC electrospray mass spectrometry (LC/ESI‐MS) method that was developed and then assessed for the specific analysis of IGF‐1 at the low levels encountered in serum. The structural identity of IGF‐1 was confirmed by endoproteinase Asp‐N digestion followed by LC/MS and LC/MS/MS characterisation. This was followed by quantification of IGF‐1 as the intact molecule against an internal standard. Copyright © 2001 John Wiley & Sons, Ltd.