Assessment of1H NMR-based metabolomics analysis for normalization of urinary metals against creatinine.
BACKGROUND
Proton nuclear magnetic resonance (1H NMR, or NMR) spectroscopy and inductively coupled plasma-mass spectrometry (ICP-MS) are commonly used for metabolomics and metal analysis in urine samples. However, creatinine quantification by NMR for the purpose of normalization of urinary metals has not been validated. We assessed the validity of using NMR analysis for creatinine quantification in human urine samples in order to allow normalization of urinary metal concentrations.


METHODS
NMR and ICP-MS techniques were used to measure metabolite and metal concentrations in urine samples from 10 healthy subjects. For metabolite analysis, two magnetic field strengths (600 and 700MHz) were utilized. In addition, creatinine concentrations were determined by using the Jaffe method.


RESULTS
Creatinine levels were strongly correlated (R2=0.99) between NMR and Jaffe methods. The NMR spectra were deconvoluted with a target database containing 151 metabolites that are present in urine. A total of 50 metabolites showed good correlation (R2=0.7-1.0) at 600 and 700MHz. Metal concentrations determined after NMR-measured creatinine normalization were comparable to previous reports.


CONCLUSIONS
NMR analysis provided robust urinary creatinine quantification, and was sufficient for normalization of urinary metal concentrations. We found that NMR-measured creatinine-normalized urinary metal concentrations in our control subjects were similar to general population levels in Canada and the United Kingdom.
Pulmonary Research Group, Department of Medicine, University of Alberta, Edmonton, AB, Canada.
Marc
M
Cassiède
Pulmonary Research Group, Department of Medicine, University of Alberta, Edmonton, AB, Canada.
Sindhu
S
Nair
Pulmonary Research Group, Department of Medicine, University of Alberta, Edmonton, AB, Canada.
Meghan
M
Dueck
Pulmonary Research Group, Department of Medicine, University of Alberta, Edmonton, AB, Canada.
James
J
Mino
Department of Chemistry, University of Alberta, Edmonton, AB, Canada.
Ryan
R
McKay
National High Field NMR Centre (NANUC), University of Alberta, Edmonton, AB, Canada.
Pascal
P
Mercier
Pulmonary Research Group, Department of Medicine, University of Alberta, Edmonton, AB, Canada.
Bernadette
B
Quémerais
Pulmonary Research Group, Department of Medicine, University of Alberta, Edmonton, AB, Canada. Electronic address: paige.lacy@ualberta.ca.
Paige
P
Lacy
D000328:Adult; D002138:Calibration; D003404:Creatinine / Q000652:urine*; D005260:Female; D006801:Humans; D009682:Magnetic Resonance Spectroscopy / Q000592:standards*; D008297:Male; D055432:Metabolomics / Q000592:standards*; D008670:Metals / Q000652:urine*; D008875:Middle Aged; D016273:Occupational Exposure / Q000032:analysis; D012015:Reference Standards; D016482:Urinalysis / Q000592:standards*; D055815:Young Adult
D008670:Metals; D003404:Creatinine
Bland-Altman plot; Creatinine quantification; Jaffe reaction method; Metal analysis; NMR; Urinary metabolite