Laxative abuse as a cause for ammonium urate renal calculi.

Nine women with laxative abuse and predominantly ammonium urate renal calculi underwent metabolic studies to identify common chemical abnormalities and determine pathophysiology. The 24-hour urine studies demonstrated marked decreases in volume (902 cm.3), sodium (28 mEq.), citrate (116 mg.) and potassium (21 mEq.). A significant elevation in ammonium urate supersaturation was found compared to control subjects when studied by the computer model EQUIL 2. Of the patients 7 had 1 or more urine specimens positive for phenolphthalein. Gastrointestinal loss of fluid and electrolytes allowed for chronic extracellular volume depletion. Intracellular acidosis was present as judged by low urinary citrate and potassium. The fact that the ion product for ammonium urate is increased significantly compared to controls reflects the stated pathophysiological changes. Laxative abuse should be suspected whenever a woman has an ammonium urate renal calculus in sterile urine.

Management of upper ureteral calculi with extracorporeal shock wave lithotripsy.

The results of 471 extracorporeal shock wave lithotripsy treatments in 465 patients with solitary ureteral stones managed by several different techniques are reported. In situ treatment was performed in 123 cases without instrumentation and in 47 after placement of a ureteral catheter. Retrograde stone manipulation was performed in 245 cases immediately before extracorporeal shock wave lithotripsy and an additional 56 were manipulated with ureteral stent placement at least 1 week before extracorporeal shock wave lithotripsy. The success rate was significantly greater if the stone was manipulated into the kidney before extracorporeal shock wave lithotripsy. Significantly less energy (p less than 0.0001) was required for complete disintegration if the stone was free floating in the kidney. The need for subsequent procedures was significantly less (p less than 0.0001) for stones manipulated successfully into the kidney. Complications were infrequent, with the most common being ureteral perforation in 5.1 per cent of the cases, all of which were managed conservatively. Extracorporeal shock wave lithotripsy is the treatment of choice for proximal ureteral calculi because it is less morbid than percutaneous approaches and provides significantly better results than ureteroscopy. An attempt at manipulation of proximal ureteral calculi back into the kidney should be made before extracorporeal shock wave lithotripsy.