Urolithiasis in patients with end stage renal failure.

Renal stones from 30 chronic hemodialysis patients were subjected to morphological study by means of microscopic examination and to constitutional analysis with infrared spectrophotometry. In 29 patients calculi could be classified into 3 main types: 1) protein stones made of pure proteins or with a protein core and less than 30% calcium oxalate (9 cases, or 30%)--they were observed predominantly in patients with primary glomerular disease, 2) oxalo-protein stones with a core of calcium oxalate and a total stone content of more than 30% calcium oxalate (15 cases, or 50%)--they appeared to be related to metabolic factors, such as high urinary oxalate and low urinary citrate concentration, and to iatrogenic factors, namely vitamin D3 and calcium salt supplementation, and 3) aluminum-magnesium urate stones, probably induced by aluminum overload (6 cases, or 20%). Thus, our study indicates that a significant proportion (70%) of stones formed by hemodialysis patients may be due to metabolic and iatrogenic factors. Our data suggest that accurate analysis of such stones provides useful information on pathogenetic factors and consequently may give clues to their prophylaxis.