Infection Play a Key Role in the Formation of Calcium Oxalate Stone: A New Hypothesis Starting from the Composition of Early DJ Stent Encrustations

Abstract

Abstract Background/aims: At present, the mechanism of calcium oxalate(CaOx) stone formation is still unclear. Previous studies have shown that the compositions of encrustations on double-J(DJ) stents were basically consistent with the compositions of primary stones, which may be a special form of stone recurrence. Therefore, we tried to identify the compositions of early encrustations and combined with some clinical findings and existing evidence to discover the a new potential direction for mechanism research of CaOx stone formation. Methods We retrospectively analyzed the data of 251 patients with upper urinary tract stones who underwent percutaneous nephrolithotomy (PCNL), ureteroscopic lithotripsy (URL), or retrograde renal surgery (RIRS). F4.8 DJ stents were indwelled after operation in all patients and were removed after 1 month. we collected early encrustations (if occurred) and purulent floccules (if found in surgery) for compositional analysis. In addition, we accidentally obtained gout crystals and dental calculus from a gout patient, and conducted a compositional analysis of them out of interest. Results All of these patients were left with DJ stents for 1 month, and 5.18% of them had encrustations on the DJ stents (early encrustations). The main compositions of these scabs were infectious compositions, without a single CaOx. Primary infectious stone and urease-producing bacteria before surgery were the risk factors for early encrustation. The compositions of purulent floccules were mainly composed of infectious compositions such as CaAp. The compositions of gout crystals were sodium urate monohydrate, CaOx dihydrate and MAP hexahydrate, and the compositions of dental calculus also contained CaOx. Conclusion Infectious compositions were the main components of early DJ stent encrustations. Infection may play a indispensable role in the formation of CaOx stone, which deserves further research.