Age-related changes of urine calcium excretion after extracorporeal shock wave lithotripsy due to artificial renal calcium leakage.

INTRODUCTION Extracorporeal shock wave lithotripsy (ESWL) is the standard stone treatment. Increased excretion of tubular enzymes and hypercalciuria has been reported after ESWL. We investigated the importance of renally induced hypercalciuria after ESWL. MATERIAL AND METHODS 30 calcium oxalate stoneformers (23 men, 7 women), mean age 53.3 (range 30-71) years, were evaluated prospectively. Plasma calcium and creatinine concentrations and 8-hour overnight urine were measured before ESWL and on the 1st and 2nd days after ESWL. To estimate the changes of tubular reabsorption, the calcium/creatinine clearance ratios were calculated. RESULTS Hypercalciuria (>5 mmol/24 h) was seen in 5/30 (16.7%) before, in 12/30 (40.0%) on day 1 and in 13/30 (43.3%) on day 2 after ESWL. The mean plasma levels of calcium were significantly decreased from 2.36 mmol/l before to 2.28 mmol/l on day 2 after ESWL (p< 0.01). The mean calcium/creatinine clearance ratio was significantly increased from 0.012 before to 0.019 after ESWL (p< 0.01). Before and on day 2 after ESWL, the calcium/creatinine clearance ratio was significantly correlated with the age of the patients (r = 0.33, p< 0.04). CONCLUSION Our data show an age-related significantly increased urine calcium excretion after ESWL possibly due to decreased tubular calcium reabsorption.