|
|
Background: Pre-analytical factors like improper urine storage may distort uric acid measurements. This case demonstrates how refrigeration-induced urate crystallization causes falsely low urine uric acid (UUA), complicating hyperuricemia management.
Methods: A 61-year-old diabetic male with normal serum uric acid (221 µmol/L) showed discordant UUA results (initial: 6,823 µmol/L vs. repeat: 3,500 µmol/L). Laboratory tests assessed pH adjustment, temperature effects, and 24-hour UUA to identify crystallization interference.
Results: Refrigeration reduced UUA by 48.7%. NaOH-mediated pH adjustment (pH 8.0) dissolved crystals, restoring UUA to 8,826 µmol/L. 24-hour UUA (3,756 µmol/24 hour) aligned with clinical expectations. Temperature and pH critically impacted urate solubility.
Conclusions: Urate crystallization causes UUA pseudodeficiency. Laboratories should prioritize immediate testing or pH adjustment. Clinicians must recognize pre-analytical pitfalls to avoid diagnostic misclassification.
DOI: 10.7754/Clin.Lab.2025.250415
|
