Improved turbidimetric assay for lysozyme in urine

Area of Science:

• Biochemistry
• Clinical Chemistry
• Urology

Background:

• Lysozyme is a key enzyme in innate immunity.
• Urinary lysozyme levels can indicate renal dysfunction.
• Accurate measurement of urinary lysozyme is crucial for diagnosis.

Purpose of the Study:

• To describe an improved turbidimetric assay for quantifying lysozyme in urine.
• To evaluate the assay's performance characteristics and clinical utility.

Main Methods:

• Development of a turbidimetric assay using commercially available reagents.
• Assessment of assay linearity, sensitivity, reproducibility, and interference.
• Establishment of reference values in 169 healthy individuals.
• Clinical evaluation in pediatric patients with renal disorders.

Main Results:

• The assay is simple, reproducible, linear over a 100-fold range, and sensitive to 10 µg/L.
• Within-run and between-run coefficients of variation (CV) were 9.9% and 4.8% for normal urine.
• Mean analytical recovery was 104.8% with minimal chemical interference.
• Significant differences observed based on Micrococcus lysodeikticus preparations and lysozyme standards.
• Clinical efficacy demonstrated in children with renal disorders, especially chronic renal failure and tubular dysfunction.

Conclusions:

• The improved turbidimetric assay provides a reliable and sensitive method for measuring urinary lysozyme.
• This assay is valuable for diagnosing and monitoring renal conditions in pediatric patients.
• Standardization of reagents and standards is important for accurate results.