Diagnostic role of urinary CA-2 in urinary stones and its prediction of complications

Background: Carbonic anhydrase-2 (CA-2) is involved in the mineralization and calcification of organisms. Evidence suggests that CA-2 is associated with urolithiasis. However, the relationship between CA-2 and urinary stones remains unclear. The study aimed to assess the correlation of urinary CA-2 (uCA-2) level with the risk of urinary stones.

Methods: A retrospective cohort study was conducted on patients with urinary stones and healthy subjects who presented to our hospital between March 2017 and November 2019 to determine the pretreatment uCA-2 level by enzyme linked immunosorbent assay (ELISA). Differences in uCA-2 levels between patients with urinary stones and healthy subjects were compared. Then, comparison between stone patients with complications and those without was carried out as well as correlation analysis to detect factors associated with biomarker expression.

Results: Patients with urinary stones (n=118) were designated the urinary stones group and healthy subjects (n=42) were designated the healthy control group. The mean pretreatment uCA-2 level was significantly higher in cases than in controls (P=0.028). Furthermore, the uCA-2 level had a positive correlation with urinary stone-associated complications (R=0.379, P<0.001), especially pain (R=0.524, P<0.001) and hematuria (R=0.374, P<0.001). Receiver operating characteristic curve (ROC) analysis revealed that a uCA-2 level threshold of 10.94 ng/mL had 83.67% sensitivity and 68.12% specificity for predicting complications in patients with urinary stones.

Conclusion: Excessive uCA-2 excretion is a major risk factor for urinary stones. Our findings suggest that uCA-2 may be used as a novel biomarker for the diagnosis of urinary stones and the prediction of its complications.