Validation and Clinical Evaluation of an LC-MS/MS Method for Serum Full-Length Parathyroid Hormone 1-84 with Application to Chronic Kidney Disease.

Objective

Accurate measurement of full-length parathyroid hormone (PTH) 1-84 is important for evaluating disorders of calcium-phosphate metabolism, particularly in chronic kidney disease (CKD). Because immunoassay results may vary according to assay design and analyte recognition, we developed and validated a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for selective quantification of serum PTH 1-84 and explored its potential clinical relevance in kidney-related disease.

Methods

Serum samples were processed by solid-phase extraction and spiked with an isotope-labeled internal standard. PTH 1-84 was separated on a C4 column and detected in positive electrospray ionization mode using multiple reaction monitoring. Analytical performance, including selectivity, linearity, accuracy, precision, recovery, and matrix effect, was evaluated using predefined acceptance criteria. A retrospective clinical analysis was then performed to compare this method with chemiluminescent immunoassay (CLIA) and to assess associations with calcium-phosphate metabolism markers.

Results

The assay showed satisfactory analytical performance with negligible matrix effect and no meaningful interference under the tested conditions. In uremic patients, PTH concentrations measured by LC-MS/MS were generally lower than those obtained by CLIA, although the two methods remained correlated. PTH 1-84 measured by LC-MS/MS showed a stronger association with serum phosphate than with serum calcium in this cohort. In patients with renal involvement, both methods showed higher PTH concentrations than in patients without renal involvement.

Conclusion

This LC-MS/MS assay provides selective quantification of serum full-length PTH 1-84 with satisfactory analytical performance. It may serve as an orthogonal analytical approach for studies of mineral metabolism in CKD-related disease, although intermethod differences should be interpreted cautiously.