The study of interferences for diagnosing albuminuria by matrix-assisted laser desorption ionization/time-of-flight mass spectrometry.
BACKGROUND
Matrix-assisted laser desorption ionization/time-of-flight (MALDI-TOF) mass spectrometric analysis of albumin (ALB) biomarkers is an alternative approach toward the rapid diagnosis of proteinuria for screening a large number of samples. The aim of this study is to reveal if interfering factors in urinary dipstick approach would affect the results of diagnosing albuminuria by MALDI-TOF MS.


METHODS
The effects of various interfering chemicals on the diagnosis of albumin in urine were examined using both MALDI-TOF mass spectrometric and dipstick approaches. Semi-quantification of albumin was performed by using MALDI-TOF MS.


RESULTS
Interferences from various drugs, detergents, vitamins and their metabolites, alkaline, and blood, which often cause false-positive and false-negative results in conventional urinary dipstick analysis, are avoided when using this MALDI-TOF MS approach. It was found that the intensity of +1 and +2 albumin ions varies with the albumin concentration. A log/log plot of the intensity ratio vs. albumin concentration is then used as a calibration curve for semi-quantifying the albumin in urines.


CONCLUSIONS
MALDI-TOF MS is an effective approach toward avoiding interferences caused by various chemical compounds during the rapid diagnosis of albumin in urine. Semi-quantification of albuminuria is also achieved by this MALDI-TOF MS approach.
Department of Chemistry, National Sun Yat-Sen University, Kaohsiung, Taiwan.
Yi-Tzu
YT
Cho
Yu-Syuan
YS
Chen
Jia-Lun
JL
Hu
Jentaie
J
Shiea
Shih Meng
SM
Yeh
Hung-Chun
HC
Chen
Yi-Chern
YC
Lee
Deng-Chyang
DC
Wu
D000328:Adult; D000368:Aged; D000419:Albuminuria / Q000175:diagnosis* / Q000652:urine*; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods / Q000592:standards*; D055815:Young Adult