What does this research mean for the field?

A newly developed liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay accurately quantifies proinsulin and its partially processed forms in human plasma at standard clinical flow rates, overcoming the cross-reactivity limitations of traditional immunoassays. Novelty: ClaimNovelty.METHODOLOGICAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

What question did this study set out to answer?

To develop and validate a standard-flow LC-MS/MS assay using peptide immunoaffinity enrichment and characterized calibrators to accurately quantify proinsulin and its intermediate cleavage forms in human plasma.

August 23, 2026Clinical Chemistry

Quantification of Proinsulin in Human Plasma by Proteolysis-Aided Peptide Immunoaffinity-Liquid Chromatography-Tandem Mass Spectrometry

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To develop and validate a standard-flow LC-MS/MS assay using peptide immunoaffinity enrichment and characterized calibrators to accurately quantify proinsulin and its intermediate cleavage forms in human plasma.
Plasma samples underwent protein precipitation, enzymatic digestion with Glu-C, and peptide immunoaffinity enrichment targeting two cleavage-site surrogate peptides (RGFFYTPKTRREAE and GSLQKRGIVE).
Analysis was conducted using LC-MS/MS calibrated against a purified protein standard characterized by HPLC and amino acid analysis.
Within-batch and between-batch imprecision were ≤12.2% and ≤16.4%, with assay linearity ranges of 0.14–53.5 pM and 1.1–91.6 pM, and lower limits of the measuring interval at 2.8 pM and 8.8 pM for the two surrogate peptides.
Plasma des-31,32-proinsulin levels showed greater increases during childhood than intact proinsulin, and individuals positive for type 1 diabetes autoantibodies exhibited elevated proinsulin-to-C-peptide ratios.
Direct comparison with two commercial immunoassays demonstrated variable cross-reactivity with insulin, confirming superior selectivity of the LC-MS/MS approach.

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Implication

Method development study demonstrates robust plasma proinsulin quantification via LC-MS/MS, highlighting enhanced specificity over standard clinical immunoassays.

Cite This Study

Shijo et al. (2026) studied this question.

synapsesocial.com/papers/6a8aade47677a3411444658f https://doi.org/10.1093/clinchem/hvag105

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Implication

Method development study demonstrates robust plasma proinsulin quantification via LC-MS/MS, highlighting enhanced specificity over standard clinical immunoassays.

Quantification of Proinsulin in Human Plasma by Proteolysis-Aided Peptide Immunoaffinity-Liquid Chromatography-Tandem Mass Spectrometry

Key Points

Discussion

Implication

Cite This Study

Quantification of Proinsulin in Human Plasma by Proteolysis-Aided Peptide Immunoaffinity-Liquid Chromatography-Tandem Mass Spectrometry

Key Points

Discussion

Implication

Cite This Study

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