Characteristics of Normalization Methods in Quantitative Urinary Metabolomics-Implications for Epidemiological...

Area of Science:

• Metabolomics
• Biochemistry
• Epidemiology

Background:

• Quantitative urinary metabolomics relies on accurate data normalization.
• Normalization methods can influence the interpretation of metabolite concentrations.

Purpose of the Study:

• To systematically compare the effects of seven normalization schemes in urinary metabolomics.
• To evaluate how normalization impacts metabolite-metabolite and metabolite-clinical associations.

Main Methods:

• Analysis of morning spot urine samples from 994 individuals using nuclear magnetic resonance (NMR) spectroscopy.
• Quantification of 44 metabolites and assessment of their associations with each other and with body mass index and mean arterial pressure.

Main Results:

• Normalization methods showed distinct effects on intra-urine metabolite associations compared to clinical associations.
• Epidemiological association patterns remained consistent across different normalization methods.
• Multimetabolite normalization schemes aligned with creatinine normalization.

Conclusions:

• Normalization method has minor influence on standard epidemiological regression analyses with clinical measures.
• Interpretation of intra-urine metabolite associations requires careful consideration of normalization methods.
• Understanding normalization's physiological basis is key for nuanced interpretation.