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

Area of Science:

• Clinical Chemistry
• Analytical Chemistry
• Biochemistry

Background:

• Mass spectrometry (MS) offers superior analytical advantages over traditional immunoassays for serum thyroglobulin (Tg) measurement.
• Widespread clinical adoption of MS-based Tg assays is hindered by limited accessibility, sensitivity issues, and lack of standardization tools.

Purpose of the Study:

• To develop and validate a sensitive and harmonizable liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay for serum thyroglobulin quantification.
• To address the limitations hindering the clinical implementation of MS-based thyroglobulin testing.

Main Methods:

• Developed an LC-MS/MS assay incorporating peptide immunoaffinity purification with a monoclonal antibody.
• Optimized the assay by modifying the mobile phase with dimethylsulfoxide (DMSO) to enhance peptide signal intensity.
• Created a novel, serum-based, 5-point distributable reference material (Husky Ref) for assay calibration and harmonization.

Main Results:

• The developed assay achieved a lower limit of quantification of 0.15 ng/mL with <20% CV.
• Addition of DMSO to the mobile phase resulted in at least a 3-fold increase in signal intensity, improving low-concentration quantification.
• Calibration using the Husky Ref material facilitated successful harmonization between laboratories in an interlaboratory study.

Conclusions:

• Sensitive serum thyroglobulin measurement via mass spectrometry is feasible using immunoaffinity purification and DMSO-enhanced mobile phase.
• The assay protocol, standard operating procedure, and Husky Ref reference material are available to facilitate laboratory adoption.
• This work provides a pathway for broader implementation of accurate and standardized MS-based thyroglobulin testing in clinical settings.