CCQM-K177 - Determination of growth hormone in serum using isotope dilution mass spectrometry

Main text This comparative measurement aims to demonstrate the ability to determine the amount of substance of a small protein in a biological matrix such as blood serum in the concentration range around 0.50 pmol/g (0.23 pmol/g to 0.90 pmol/g) using isotope dilution mass spectrometry. Growth Hormone (GH) was selected as the model protein, with the measurand being total GH in serum. A pooled serum sample from blood donors was used as study material. Five National Metrology Institutes (NMIs) participated and submitted results, all of which were included in the calculation of the key comparison reference value. All participants agreed to use the DerSimonian and Laird method to establish the consensus value. Due to greater-than-expected variability among participants compared to the uncertainties reported by their laboratories, an excess measurement uncertainty (referred to as "dark uncertainty") was estimated. This value provided a quantitative assessment of previously unidentified uncertainty components. The DerSimonian and Laird consensus value was determined to be 11.79 ± 0.99 ng/g, with the dark uncertainty (τ) estimated at 2.09 ng/g. To reach the main text of this paper, click on Final Report . Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/ . The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).