Development and validation of a rapid liquid chromatography isotope dilution tandem mass spectrometry (LC-IDMS/MS) method for serum creatinine.
OBJECTIVE
To develop an isotope dilution liquid chromatography tandem mass spectrometry (LC-IDMS/MS) method for the standardization of serum creatinine.


METHODS
Supernatants obtained by protein precipitation were injected into a LC-MS/MS. Chromatography was performed on a cation exchanger pre-column in normal phase isocratic mode. Creatinine and creatinine-D(3) were quantified using ion transitions of m/z 114-->44 and 117-->47, respectively.


RESULTS
The method was calibrated with the NIST Standard Reference Material 914a and was found to be exact in analyzing the certified reference material SRM 967 from NIST (97.1+/-0.9% and 102.1+/-0.9% of target value for levels 1 and 2, respectively) and by calculating recuperation of spiked creatinine in 10 different patient samples (103.6+/-4.1%). Intra-assay imprecision was 0.9% at both 64.6 and 354 micromol/L creatinine, while inter-assay imprecisions were 1.9% and 1.8%. Absence of ion suppression was confirmed by spiking experiments. The method was shown to be free of carryover. A good correlation was obtained between the LC-MS/MS method and a Jaffe method run on an automated analyzer (r=0.999).


CONCLUSIONS
We have developed a fast and simple method for the quantification of serum creatinine by isotope dilution tandem mass spectrometry (IDMS/MS) and we propose that this method can be used as a reference method by laboratories that wish to validate their serum creatinine automated assay.
Hétu
Pierre-Olivier
PO
Department of Biochemistry, Hôpital Notre-Dame, Centre Hospitalier de l'Université de Montréal, Montréal, Québec, Canada. pierre-olivier.hetu.chum@ssss.gouv.qc.ca
Gingras
Marie-Eve
ME
Vinet
Bernard
B
D002138:Calibration; D002853:Chromatography, Liquid / Q000379:methods* / Q000592:standards; D003404:Creatinine / Q000097:blood* / Q000592:standards; D006801:Humans; D012015:Reference Standards; D053719:Tandem Mass Spectrometry / Q000379:methods* / Q000592:standards
D003404:Creatinine