title: Targeted selected reaction monitoring mass spectrometric immunoassay for insulin-like growth factor 1.
abstract: Insulin-like growth factor 1 (IGF1) is an important biomarker of human growth disorders that is routinely analyzed in clinical laboratories. Mass spectrometry-based workflows offer a viable alternative to standard IGF1 immunoassays, which utilize various pre-analytical preparation strategies. In this work we developed an assay that incorporates a novel sample preparation method for dissociating IGF1 from its binding proteins. The workflow also includes an immunoaffinity step using antibody-derivatized pipette tips, followed by elution, trypsin digestion, and LC-MS/MS separation and detection of the signature peptides in a selected reaction monitoring (SRM) mode. The resulting quantitative mass spectrometric immunoassay (MSIA) exhibited good linearity in the range of 1 to 1,500 ng/mL IGF1, intra- and inter-assay precision with CVs of less than 10%, and lowest limits of detection of 1 ng/mL. The linearity and recovery characteristics of the assay were also established, and the new method compared to a commercially available immunoassay using a large cohort of human serum samples. The IGF1 SRM MSIA is well suited for use in clinical laboratories.
authors.affiliation: Thermo Fisher Scientific, Tempe, Arizona, United States of America.
authors.forename: Eric E
authors.initials: EE
authors.lastname: Niederkofler
authors.forename: David A
authors.initials: DA
authors.lastname: Phillips
authors.forename: Bryan
authors.initials: B
authors.lastname: Krastins
authors.forename: Vathany
authors.initials: V
authors.lastname: Kulasingam
authors.forename: Urban A
authors.initials: UA
authors.lastname: Kiernan
authors.forename: Kemmons A
authors.initials: KA
authors.lastname: Tubbs
authors.forename: Scott M
authors.initials: SM
authors.lastname: Peterman
authors.forename: Amol
authors.initials: A
authors.lastname: Prakash
authors.forename: Eleftherios P
authors.initials: EP
authors.lastname: Diamandis
authors.forename: Mary F
authors.initials: MF
authors.lastname: Lopez
authors.forename: Dobrin
authors.initials: D
authors.lastname: Nedelkov
mesh_terms: D015415:Biomarkers / Q000097:blood; D006801:Humans; D007118:Immunoassay / Q000379:methods* / Q000592:standards; D007334:Insulin-Like Growth Factor I / Q000737:chemistry / Q000378:metabolism*; D013058:Mass Spectrometry / Q000379:methods* / Q000592:standards; D012015:Reference Standards; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D015415:Biomarkers; D007334:Insulin-Like Growth Factor I