This study introduces a novel two-enzyme method for accurately measuring urinary oxalate levels using continuous-flow analysis. The method provides reliable quantification of oxalate, crucial for diagnosing and managing related health conditions.
Area of Science:
Biochemistry
Analytical Chemistry
Clinical Chemistry
Background:
Urinary oxalate is a key biomarker for kidney stone formation and other metabolic disorders.
Accurate quantification of urinary oxalate is essential for clinical diagnosis and patient management.
Existing methods for urinary oxalate estimation may have limitations in sensitivity, specificity, or throughput.
Purpose of the Study:
To develop and validate a robust two-enzyme method for the precise determination of urinary oxalate.
To establish reference ranges for urinary oxalate excretion in a healthy population.
To assess the analytical performance characteristics of the new method.
Main Methods:
A continuous-flow analysis system was employed, utilizing a two-enzyme reaction cascade.
Oxalate was decarboxylated to formate, which was then oxidized to NADH in the presence of NAD+.
NADH was quantified colorimetrically, with urine pretreated via oxalate precipitation and citrate buffer extraction.
Recovery of [U-14C]oxalic acid was used to correct for extraction efficiency.
Main Results:
The method demonstrated high analytical recovery (mean 95%, SD 10%) with added unlabeled oxalate.
Within-assay and between-assay coefficients of variation (CV) were low (3.2% and 7.6%, respectively).
The normal range for urinary oxalate was determined to be 0.20–0.52 mmol/24h (18–47 mg/24h), with a mean of 0.37 mmol/24h (33 mg/24h).
Conclusions:
The presented two-enzyme method offers a reliable and accurate approach for estimating urinary oxalate.
This method is suitable for routine clinical laboratory use due to its efficiency and precision.
The established normal ranges provide a valuable reference for clinical interpretation of urinary oxalate levels.
