Interlaboratory agreement of insulin-like growth factor 1 concentrations measured by mass spectrometry

Holly D Cox, Filipe Lopes, Getachew A Woldemariam, Jessica O Becker, Mark C Parkin, Andreas Thomas, Anthony W Butch, David A Cowan, Mario Thevis, Larry D Bowers, Andrew N Hoofnagle

Research output: Contribution to journalArticlepeer-review

94 Citations (Scopus)

Abstract

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.

METHODS: We deployed an LC-MS/MS method to quantify serum IGF-1 in 5 laboratories using 5 different instruments and analyzed 130 healthy human samples and 22 samples from patients with acromegaly. We determined measurement imprecision (CV) for differences due to instrumentation, calibration curve construction, method of calibration, and reference material.

RESULTS: Instrument-dependent variation, exclusive of digestion, across 5 different instrument platforms was determined to be 5.6%. Interlaboratory variation was strongly dependent on calibration. Calibration materials from a single laboratory resulted in less variation than materials made in individual laboratories (CV 5.2% vs 12.8%, respectively). The mean imprecision for 152 samples between the 5 laboratories was 16.0% when a calibration curve was made in each laboratory and 11.1% when a single-point calibration approach was used.

CONCLUSIONS: The interlaboratory imprecision of serum IGF-1 concentrations is acceptable for use of the assay in antidoping laboratories and in standardizing results across clinical laboratories. The primary source of variability is not derived from the sample preparation but from the method of calibration.
Original languageEnglish
Pages (from-to)541-548
Number of pages8
JournalClinical Chemistry
Volume60
Issue number3
DOIs
Publication statusPublished - Mar 2014

Keywords

  • Acromegaly
  • Calibration
  • Case-Control Studies
  • Chromatography, Liquid
  • Humans
  • Immunoassay
  • Insulin-Like Growth Factor I
  • Tandem Mass Spectrometry

Fingerprint

Dive into the research topics of 'Interlaboratory agreement of insulin-like growth factor 1 concentrations measured by mass spectrometry'. Together they form a unique fingerprint.

Cite this