Urolithiasis Risk Factors Following Extracorporeal Shock Wave Lithotripsy

Abstract

A 24-hour urine collection was made in 43 randomly selected patients (11 female, 32 male), one to three months following extracorporeal shock wave lithotripsy (ESWL) with a Dornier HM₃ lithotripter at Humana/Medical City Dallas. In order to better reveal metabolic abnormalities, each patient followed a restricted diet (low in calcium, sodium, and meat) and did not take medications which can affect the results of these studies.

The majority of patients (60%) had multiple risk factors. Low volume (51%) and hypocitraturia (49%) were most commonly observed. Hypercalciuria was present in 30% of cases. Elevated ammonia excretion, probably due to infection, was detected in 21%. A completely normal profile was found in 7%, with another 9% normal except for low volume, suggesting that no metabolic abnormalities were present in these patients. High, relative saturations of calcium oxalate and uric acid were observed in many cases but were generally normal, indicating that stone disease was rather modest in this group. These results imply that the majority of patients, following ESWL, present with abnormalities predisposing to recurrent stone formation; therefore, therapeutic intervention is required in order to prevent continued stone disease.