Endotoxin content in renal calculi

Purpose: Manipulation of infection calculi (struvite and calcium apatite) can cause the sepsis syndrome due to endotoxemia or bacteremia. We sought to determine whether concentrations of endotoxin sufficient to produce the sepsis syndrome could be embedded in renal infection stones. Materials and Methods: Fragments of infection and noninfection renal calculi were processed and assayed for endotoxin concentration. Endotoxin concentrations, recorded as endotoxin units per gm. calculus, were converted to ng. (10 endotoxin units = 1 ng.). Urine culture results were available for some patients with infection stones. Results: A total of 34 renal calculi (16 infection and 18 noninfection) were evaluated. The composition of 62.5% of the infection stones was struvite, whereas 50% of the noninfection stones were calcium oxalate monohydrate. Mean endotoxin concentration in infection calculi was 12,223 ng./gm. stone (range 0.6 to 50,000), compared to 340.3 ng./gm. stone (range 0 to 3,490) in noninfection calculi. The endotoxin content difference was significant (p = 0.001). Urine culture results available from 9 patients with infection stones did not correlate with endotoxin concentrations. Conclusions: Large endotoxin concentrations can be found in renal infection calculi. Noninfection stones can contain endotoxin but in much lower amounts. Massive endotoxin release could occur with infection stone manipulation, possibly producing increased serum endotoxin concentrations similar to those seen in gram-negative sepsis. Anti-endotoxin strategies may be beneficial in preventing and treating stone induced endotoxemia and the sepsis syndrome.