24-h urine test application in patients with kidney stone disease: a population-based study in a primary care setting.

Background: Kidney stone formation is driven by an imbalance between lithogenic substances and crystallization inhibitors. Current guidelines recommend a 24-h urine collection in patients with kidney stone disease to assess the risk of stone formation and monitor therapy compliance. However, real-world data on adherence to these guidelines remain limited and outdated.

Methods: We used the Health Search Database to examine laboratory test data of patients with kidney stone disease between 2013 and 2022 in Italy. Adults with at least one episode of kidney or ureteral stones during this period were included. We used the prescription of urinary calcium, oxalate, and citrate levels as a proxy for full metabolic testing.

Results: A total of 21,907 adult patients were identified (44.6% women). Only 4.8% (n = 1059) underwent 24-h urine testing, and just 0.6% had all three target measurements. Testing rates were slightly higher in recurrent stone formers (6.1%). The likelihood of receiving a test increased nearly sixfold after a nephrology visit (OR 6.09, 95% CI 5.27-7.05, p < 0.001), compared to a lower increase after urology visits (OR 1.95, 95% CI 1.71-2.23, p < 0.001). Nonetheless, fewer than 10% of kidney stone disease patients consulted a nephrologist, and only half of those with coexisting chronic kidney disease (CKD) had such a referral.

Conclusion: Awareness of 24-h urine testing and nephrology referral in stone formers remains low, despite their role in guiding personalized treatment. Promoting their use could enhance patient care by identifying urinary abnormalities and reducing the risk of recurrence and complications.