Comparison of representative ranges based on U.S. patient population and literature reference intervals for urinary...

Area of Science:

• Environmental Chemistry
• Clinical Chemistry
• Analytical Chemistry

Background:

• Defining non-exposed populations for trace element reference intervals is difficult.
• Representative ranges from general patient populations offer valuable interpretations for laboratory results.
• Urinary trace element analysis requires normalization for urine concentration variability.

Purpose of the Study:

• To establish representative ranges for 25 urinary trace elements in a general US patient population.
• To compare two statistical methods for calculating these reference ranges.
• To assess the utility of creatinine-adjusted concentrations for trace element analysis.

Main Methods:

• Analysis of 25 urinary trace elements using inductively-coupled plasma-mass spectrometry and graphite furnace atomic absorption spectroscopy.
• Calculation of representative ranges using non-parametric (discarding top 10%) and parametric (outlier removal) methods.
• Normalization of trace element concentrations using urine creatinine ratios to correct for dilution.

Main Results:

• Two calculation methods yielded similar results for most analytes, performing well for 14 elements.
• Minor discrepancies were observed for 7 analytes, and major discrepancies for 4 analytes.
• Creatinine adjustment effectively normalized urinary trace element concentrations.

Conclusions:

• Representative ranges for urinary trace elements can be derived from general patient populations.
• Both non-parametric and parametric methods are viable for establishing these ranges, with minor variations.
• Creatinine correction is essential for accurate interpretation of random urine trace element measurements.