Moncrieffe, Danielle, Cox, Holly D., Carletta, Samantha, Becker, Jessica O., Thomas, Andreas, Eichner, Daniel, Ahrens, Brian, Thevis, Mario, Bowers, Larry D., Cowan, David A. and Hoofnagle, Andrew N. (2020). Inter-Laboratory Agreement of Insulin-like Growth Factor 1 Concentrations Measured Intact by Mass Spectrometry. Clin. Chem., 66 (4). S. 579 - 587. CARY: OXFORD UNIV PRESS INC. ISSN 1530-8561
Full text not available from this repository.Abstract
BACKGROUND: Insulin-like growth factor-I (IGF-1) is measured mainly by immunoassay for the diagnosis and treatment of growth hormone (GH) disorders, and to detect misuse of GH in sport. Immunoassays often have insufficient inter-laboratory agreement, especially between commercial kits. Over the expected range of IGF-1 in blood (similar to 50-500 ng/mL), in an inter-laboratory study we previously established a measurement imprecision of 11% (%CV) for the digested protein analyzed by LC-MS. Measuring intact IGF-1 by LC-MS should be simpler. However, no inter-laboratory agreement has been published. METHODS: Intact and trypsin-digested IGF-1 in 32 serum samples from healthy volunteers and human growth hormone administration studies were analyzed by LC-MS using different instruments in five laboratories, as well as by immunoassay in a single laboratory. Another 100 samples were analyzed for IGF-1, both intact and after trypsin-digestion, in each laboratory by LC-MS. The statistical relationship between measurements and the imprecision of each assay group was assessed. RESULTS: An intra-laboratory variability of 2-4% CV was obtained. Inter-laboratory variability was greater at 14.5% CV. Orthogonal regression of intact versus trypsin-digestion methods (n= 646) gave a slope of 1.01 and intercept of 2.05 ng/mL. CONCLUSIONS: LC-MS measurements of IGF-1 by intact and trypsin-digestion methods are not statistically different and each is similar to immunoassay. The two LC-MS approaches may be used interchangeably or together to eliminate concerns regarding an immunoassay IGF-1 measurement. Because intact and digested IGF-1 measurements generally agreed within 20% of each other, we propose this as a criterion of assay acceptability.
| Item Type: | Journal Article | ||||||||||||||||||||||||||||||||||||||||||||||||
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| URN: | urn:nbn:de:hbz:38-339268 | ||||||||||||||||||||||||||||||||||||||||||||||||
| DOI: | 10.1093/clinchem/hvaa043 | ||||||||||||||||||||||||||||||||||||||||||||||||
| Journal or Publication Title: | Clin. Chem. | ||||||||||||||||||||||||||||||||||||||||||||||||
| Volume: | 66 | ||||||||||||||||||||||||||||||||||||||||||||||||
| Number: | 4 | ||||||||||||||||||||||||||||||||||||||||||||||||
| Page Range: | S. 579 - 587 | ||||||||||||||||||||||||||||||||||||||||||||||||
| Date: | 2020 | ||||||||||||||||||||||||||||||||||||||||||||||||
| Publisher: | OXFORD UNIV PRESS INC | ||||||||||||||||||||||||||||||||||||||||||||||||
| Place of Publication: | CARY | ||||||||||||||||||||||||||||||||||||||||||||||||
| ISSN: | 1530-8561 | ||||||||||||||||||||||||||||||||||||||||||||||||
| Language: | English | ||||||||||||||||||||||||||||||||||||||||||||||||
| Faculty: | Unspecified | ||||||||||||||||||||||||||||||||||||||||||||||||
| Divisions: | Unspecified | ||||||||||||||||||||||||||||||||||||||||||||||||
| Subjects: | no entry | ||||||||||||||||||||||||||||||||||||||||||||||||
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| URI: | http://kups.ub.uni-koeln.de/id/eprint/33926 |
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