MSACL 2024 Abstract

Interlaboratory Comparison of Antibody-Free LC-MS/MS Measurements of C-peptide and Insulin

Annie Moradian (1), Elisha Goonatileke (2), Tai-Tu Lin (3) Maya Hatten-Beck (2), Michelle Emrick (2), Athena A Schepmoes (3), Thomas L. Fillmore (3), Michael J. MacCoss (4), Salvatore Sechi (5), Kimia Sobhani (6), Randie Little (7) Kuanysh Kabytaev (7), Jennifer E. van Eyk (1,6,8) Wei-Jun Qian (3), Andrew N. Hoofnagle (2,9)
(1) Precision Biomarker Laboratories, Cedars-Sinai Medical Center, Los Angeles, CA (2) Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA (3) Integrative Omics, Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA (4) Department of Genome Sciences, University of Washington, Seattle, WA (5) National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD (6) Department of Pathology and Laboratory Medicine, Cedars-Sinai Medical Center, Los Angeles, CA (7) Department of Pathology and Anatomical Sciences, University of Missouri School of Medicine, Columbia, MO (8) Advanced Clinical Biosystems Research Institute, Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, CA (9) Kidney Research Institute, Department of Medicine, University of Washington, Seattle, WA

Annie Moradian, PhD (Presenter) Precision Biomarker Laboratories/Cedars-Sinai Medical Center

Presenter Bio: Annie Moradian is a Lead Biomedical Scientist at Precision Biomarker Laboratories at Cedars-Sinai Medical Center. Annie obtained her PhD in Analytical Chemistry from University of British Columbia. She has extensive background in both quantitative and discovery proteomics. Currently her focus is on development and optimization of new high-throughput LC-MS methods for biomarker candidate discovery and verification.

Relevant Financial Disclosures (within past 24 months, reported on Feb 06, 2025) No relevant financial relationship(s) to disclose. Discussing Products? NO, presenter will NOT present educational content related to products/services of the ineligible company(ies) listed above. Conflict mitigation NOT REQUIRED.

Background
The enhanced precision and selectivity of liquid chromatography-tandem mass spectrometry (LC-MS/MS) makes it an attractive alternative to certain clinical immunoassays. Easily transferrable workflows could help facilitate harmonization and ensure high-quality patient care. We aimed to evaluate the inter-laboratory comparability of antibody-free multiplexed insulin and C-peptide LC-MS/MS measurements.

Methods
The laboratories that comprise the NIDDK Targeted Mass Spectrometry Assays for Diabetes and Obesity Research (TaMADOR) consortium verified the performance of the validated peptide-based assay [reproducibility, linearity, and lower limit of the measuring interval (LLMI)]. An inter-laboratory comparison study was then performed using shared calibrators, de-identified leftover laboratory samples, and reference materials.

Results
During verification, the measurements were precise (2.7-3.7 %CV), linear (4 to 15 ng/mL for C-peptide and 2 to 14 ng/mL for insulin), and sensitive (LLMI of 0.04-0.10 ng/mL for C-peptide and 0.03 ng/mL for insulin). Median imprecision across the three laboratories was 13.4% (IQR 11.6%) for C-peptide and 22.2% (IQR 20.9%) for insulin using individual measurements and 10.8% (IQR 8.7%) and 15.3% (IQR 14.9%) for C-peptide and insulin, respectively, when replicate measurements were averaged. Method comparison with the University of Missouri reference method for C-peptide demonstrated a robust linear correlation with a slope of 1.044 and r2 = 0.99.

Discussion
Our results suggest that combined LC-MS/MS measurements of C-peptide and insulin are robust and adaptable and that standardization with a reference measurement procedure could allow accurate and precise measurements across sites, which could be important to diabetes research and help patient care in the future.