A distributable LC-MS/MS method for the measurement of serum thyroglobulin

• Published in: Journal of mass spectrometry and advances in the clinical lab Vol. 26; pp. 28 - 33
• Main Authors: Shi, Junyan, Phipps, William S., Owusu, Benjamin Y., Henderson, Clark M., Laha, Thomas J., Becker, Jessica O., Razavi, Morteza, Emrick, Michelle A., Hoofnagle, Andrew N.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.11.2022; Elsevier
• Subjects: Autoantibody; Differentiated thyroid cancer; from the Special Issue on Quantitative Protein Mass Spectrometry to target Unmet Clinical Need; Mass spectrometry; Thyroglobulin; LC-MS/MS; DTC; Tg; Thyroglobulin; DMSO; TLCK; Autoantibody; CPTAC; IAE; Mass spectrometry; Differentiated thyroid cancer; DMSO, dimethylsulfoxide; Tg, thyroglobulin; CPTAC, Clinical Proteomic Tumor Analysis Consortium; DTC, differentiated thyroid cancer; LC-MS/MS, liquid chromatography-tandem mass spectrometry; IAE, immunoaffinity enrichment; TLCK, tosyllysine chloromethyl ketone hydrochloride
• ISSN: 2667-145X; 2667-1468; 2667-145X
• DOI: 10.1016/j.jmsacl.2022.09.005

•Sensitive serum thyroglobulin measurement by LC-MS/MS.•Detailed standard operating procedure using a commercially available antibody.•Dimethylsulfoxide-enhanced ionization of a proteotypic thyroglobulin peptide.•Beads for peptide immunoaffinity purification can be reused at least 5 times.•Distributable standard reference material (Husky Ref) to facilitate assay harmonization. Despite its clear advantages over immunoassay-based testing, the measurement of serum thyroglobulin by mass spectrometry remains limited to a handful of institutions. Slow adoption by clinical laboratories could reflect limited accessibility to existing methods that have sensitivity comparable to modern immunoassays, as well as a lack of tools for calibration and assay harmonization. We developed and validated a liquid chromatography-tandem mass spectrometry-based assay for the quantification of serum thyroglobulin. The protocol combined peptide immunoaffinity purification using a commercially available, well-characterized monoclonal antibody and mobile phase modification with dimethylsulfoxide (DMSO) for enhanced sensitivity. To facilitate harmonization with other laboratories, we developed a novel, serum-based 5-point distributable reference material (Husky Ref). The assay demonstrated a lower limit of quantification of 0.15 ng/mL (<20 %CV). Mobile phase DMSO increased signal intensity of the target peptide at least 3-fold, improving quantification at low concentrations. Calibration traceable to Husky Ref enabled harmonization between laboratories in an interlaboratory study. Sensitive mass spectrometry-based thyroglobulin measurement can be achieved using a monoclonal antibody during peptide immunoaffinity purification and the addition of mobile phase DMSO. Laboratories interested in deploying this assay can utilize the provided standard operating procedure and freely-available Husky Ref reference material.