Utilizing Mass Spectrometry to Detect and Isotype Monoclonal Proteins in Urine: Comparison to Electrophoretic Methods.
Clin Chem
; 69(7): 746-753, 2023 07 05.
Article
en En
| MEDLINE
| ID: mdl-37228061
ABSTRACT
BACKGROUND:
Matrix assisted laser desorption ionization time of flight mass spectrometry coupled to immune enrichment (MASS-FIX) as an alternative to serum immunofixation electrophoresis has demonstrated increased sensitivity in monoclonal protein (MP) detection with improved laboratory workflow. This study explored similar replacement of urine immunofixation electrophoresis (u-IFE) with urine MASS-FIX (u-MASS-FIX) by method comparison.METHODS:
Residual urine (n = 1008) from Mayo Clinic patients with a known plasma cell disease were assayed neat by u-MASS-FIX analysis. Each sample was paired with the following u-IFE, urine total protein, urine protein electrophoresis, serum κ/λ free light chain (LC) ratio (rFLC), and serum MASS-FIX (s-MASS-FIX). Analytical sensitivities were measured in pooled urine spiked with daratumumab.RESULTS:
u-IFE and u-MASS-FIX had 91% agreement in determining the presence/absence of MPs (Cohen kappa = 0.8200). In discrepant cases, serum rFLC statistically aligned more closely with positive u-MASS-FIX cases than u-IFE. Patients positive by both s-MASS-FIX and u-MASS-FIX had matching MP masses (±20 daltons) in 94% of cases. The u-MASS-FIX spectra further identified κ/λ LC fragments and glycosylated LCs not appreciated on u-IFE. The unconcentrated u-MASS-FIX limit of detection of 0.156 mg/mL was determined equivalent to 100× concentrated u-IFE.CONCLUSION:
u-MASS-FIX is a reliable alternative to u-IFE with the added benefits of LC glycosylation detection and MP mass tracking between serum and urine. Furthermore, u-MASS-FIX is performed using neat urine. Eliminating the need to concentrate urine for u-IFE has potential to increase productivity by decreasing labor minutes per test.
Texto completo:
1
Colección:
01-internacional
Banco de datos:
MEDLINE
Asunto principal:
Paraproteinemias
Límite:
Humans
Idioma:
En
Revista:
Clin Chem
Asunto de la revista:
QUIMICA CLINICA
Año:
2023
Tipo del documento:
Article
País de afiliación:
Estados Unidos