Functional and Histologic Alterations in Growing Solitary Rat Kidney as Result of Extracorporeal Shockwaves

The long-term effects of extracorporeal Shockwave lithotripsy (SWL) on children treated for renal calculi are unclear. To study the effects on the immature animal, we evaluated 31 Wistar white rats that underwent right nephrectomy at 30 days of age. At 40 days of age they were divided into three groups: a control group of 10 rats that received no Shockwaves; Group I (9 rats) that received 1000 Shockwaves at 16.0 kV, and Group II (12 animals) that received 1000 shock waves at 17.2 kV. Six months later at maturity (7 months and 10 days of age), the following parameters were measured: (1) body and renal weight; (2) blood lithium, sodium, potassium, and creatinine; (3) fractional lithium, sodium, and potassium excretion; and (4) clearances of lithium and creatinine. The kidneys were studied grossly and histologically. We found no significant changes in overall animal and renal growth between the post-SWL and control groups. However, there were significant changes in renal function. The animals in Groups I and II presented significant increases in blood potassium compared with the control group. Furthermore, the 1000 x 17.2 kV group showed permanent histologic renal changes, including red cells in Bowman's capsule and glomerular congestion. The disorders caused by SWL are compatible with hyporeninemic hypoaldosteronism, inappropriately low plasma renin activity, and aldosterone deficiency. We conclude that although SWL does not affect either overall or renal growth, it may cause significant changes in renal function and permanent histologic damage.