#AI Reads Urine# Variable power functional dilution adjustment of spot urine

This study by Thomas Clemens Carmine introduces the Variable Power - Functional Creatinine Correction (V - PFCRC) method to address limitations in spot urinary biomarker dilution adjustments. Spot urinary biomarkers are crucial in various studies, but hydration - related variability challenges their accuracy. Traditional methods like conventional creatinine correction (CCRC) have flaws, such as inaccurate assumptions and systemic dilution adjustment errors (SDAEs), leading to inconsistent results.

The V - PFCRC method normalizes analytes to 1 g/L creatinine (CRN) using uncorrected analyte levels and two analyte - specific coefficients, c and d. Total urinary arsenic was initially used to develop the method due to its significance as an environmental toxin and the availability of a large dataset. The study used datasets from the Institute for Medical Diagnostics Berlin - Potsdam, including 5,752 spot urine samples for method development and additional datasets for validation.

Results show that V - PFCRC effectively reduces residual CRN bias and enhances blood - urine correlations for arsenic and iodine. It outperforms CCRC and simple power - functional correction (S - PFCRC) in minimizing dilution - related errors across different exposure levels. For example, in arsenic analysis, V - PFCRC significantly reduces the dependence of urinary arsenic on CRN, while CCRC often overcorrects.

However, V - PFCRC has limitations. At extreme CRN or analyte levels, issues like paradoxical adjustments and less reliable curve fits may occur. High CRN cutoffs can negatively impact power - functional curve fits, and outliers can distort results. Despite these, the method's overall performance is robust, and its formulas can be optimized for different populations.

In conclusion, V - PFCRC offers a more accurate way to manage dilution - related biases in spot urinary biomarker analysis. It can be integrated into existing laboratory software, improving the precision of clinical, epidemiological, and forensic research. Future research could focus on further refining the method to account for more confounding factors and enhance its accuracy.

Sci Rep. 2025 Jan 30;15(1):3688. doi: 10.1038/s41598-024-84442-9

Youhe Gao

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