BACKGROUND:Insulin-like growth factor 1 (IGF-1) 7 is a key mediator of growth hormone (GH) action and a well-characterized biomarker of GH abuse. Current immunoassays for IGF-1 suffer from poor concordance between platforms, which makes comparison of results between laboratories difficult. Although previous work has demonstrated good interlaboratory imprecision of LC-MS/MS methods when plasma is supplemented with purified proteins, the interlaboratory imprecision of an endogenous protein in the nanogram-per-milliliter concentration range has not been reported.

A quantitative method was developed for the quantification of intact IGF-I in human serum samples. The data generated provided important information for the development of a new reference method for the growth hormone biomarker test and helped create a reliable system for monitoring peptide hormones in individual athletes, a possible extension to the athlete biological passport system. Nano-electrospray has here been shown to be sufficiently robust for routine use in an analytical laboratory, allowing for the analysis of minute sample volumes.

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