Presentation Authors: Ethan Brinkman*, Tim Large, James Williams, Amy Krambeck, Indianapolis, IN
Introduction: Calcium oxalate (CaOx) is the most common stone type in the United States. Current AUA guidelines suggest that a 24-hour urine collections should be obtained in high-risk, interested first-time and recurrent stone formers. While these tests can add information to the patientâ€™s clinical picture and help guide a stone prevention plan, there may be situations in which a stone analysis alone can drive preventative management. Prior work has suggested that urine chemistries can influence the morphology of CaOx stone toward varying concentrations of the monohydrate (COM) or dihydrate (COD) crystal structure.
Methods: We retrospectively reviewed stone analyses from Beck Analysis laboratories database from Jan 1 2002- Jul 1 2018. We identified 1001 patients with pure COM ( pCOM=791) and pure COD (pCOD=210) who received care from our institution. 123 pCOM and 70 pCOD patients had 24-hour urinalyses completed by Litholink laboratories that could be paired with their stone analysis. Patients younger than 18 or with mixed or non-CaOx stone analyses were excluded.
Results: Results: Patient characteristics and 24-hour urine characteristics are included in Table 1. Primary hyperparathyroidism [2 COM; 3 COD], malabsorption syndromes[24 COM; 2 COD] including: surgical bowel resection/diversion, bariatric surgery or Crohnâ€™s disease, medullary sponge kidney [4 COM; 0 COD], and anatomical anomalies[9 COM; 2 COD] such as horseshoe, solitary, bifid collecting system, ectopic kidney was noted in the cohort. Comparison of pCOM and pCOD patients (Figure 1) showed correlation with hyperoxaluria (51.2% vs 31.4% p < 0.01) and hypercalciuria (23.6% vs 72.9% p < 0.0001) respectively.
Conclusions: Conclusion: Our results align with prior studies suggesting that a stone analysis represents an aggregate of crystal deposition over a prolonged period and may be representative of underlying urinary derangements. In patients with predominant or pure COD, in whom a 24-hr urinalysis is not available, treatment of underlying hypercalciuria will likely aid in the prevention of further stone events.