ALTERATIONS IN PREDICTED GROWTH-RATES OF PEDIATRIC KIDNEYS TREATED WITH EXTRACORPOREAL SHOCKWAVE LITHOTRIPSY

The long-term effects of extracorporeal shockwave lithotripsy (SWL) on the kidneys of children treated for renal calculi are unclear, In ord er to determine if SWL has any negative effects on renal growth rates, we reviewed long-term (mean 9-year) follow-up data on 29 pediatric pa tients treated between 1984 and 1988 with an unmodified Dornier HM3 li thotripter, Changes in renal length, serum creatinine, and blood press ure were analyzed, Predicted renal growth was calculated using a formu la for age-adjusted renal length. Treated kidneys were stratified into normal and abnormal groups based on a history of renal surgery, evide nce of recurrent infection, and obvious anatomic abnormalities. Fifty- six upper urinary tract calculi were treated in 34 renal units. Twenty -two renal units (68%) were rendered stone free, and 65% of the patien ts continue to be stone free. At follow-up, one patient was classified as having new-onset hypertension, and the mean serum creatinine was 0 .93 +/- 0.08 mg/dL. Both at treatment and at follow-up, no significant differences were found in the sizes of the treated and untreated kidn eys. However, at treatment, the abnormal group of kidneys seemed to be smaller than expected (mean Z -1.30 +/- 1.10), whereas the group of n ormal kidneys was very close (mean Z 0.18 +/- 0.54) to the predicted l ength. At follow-up, the deviations between actual and predicted renal length were significantly more negative. Treated kidneys were an addi tional 1.26 +/- 0.49 SD units below their expected length (p = 0.02), Untreated kidneys were further below normal as well but possibly to a lesser degree (-0.82 +/- 0.36; p < 0.04). Although there was a trend f or the abnormal group to have smaller kidneys than the normal group, b oth groups showed the same trend toward an age-adjusted reduction in r enal growth at follow-up. The alterations in renal growth patterns obs erved in this population are unsettling and could be secondary to eith er treatment effect (SWL) or, more likely, to some underlying patholog y intrinsic to pediatric kidneys with urolithiasis, Until further data are available, SWL in the pediatric population should be applied with caution and at the lowest dosage sufficient to achieve stone comminut ion.