CYSTINE CALCULI : Diagnosis and Management - 11/09/11
Résumé |
It has been nearly two centuries since Wollaston78 first described the presence of an unusual chemical component in bladder calculi, which he termed cystic oxide. Observing the absence of an oxide moiety, Berzelius3 renamed the compound cystine, but it was not until 1902 that Friedman23 finally elucidated the chemical structure of cystine. Cystinuria is recognized today as the excessive excretion into the urine of the four basic amino acids cystine, lysine, ornithine, and arginine (Figure 1). Of these, only cystine is relatively insoluble at ordinary urinary pHs.74 Patients afflicted with cystinuria produce a supersaturated urine and are at risk for cystine crystallization and stone formation. For this reason, the only phenotypically important feature of cystinuria is the predisposition toward calculi in the urinary tract. Nutritional deficiencies of the essential dibasic amino acids lysine and arginine do not occur in cystinurics because the jejunal enzymatic defect responsible for their transport as monomers does not affect their absorption in dipeptide form.32 , 66
Overall, cystine stones represent 1% to 2% of urinary calculi.42 , 50 The worldwide prevalence of homozygous cystinuria varies considerably, affecting 1 per 15,000 persons in the United States but as many as 1 in 2500 Jews of Libyan extraction51 , 77 ; furthermore, it is a clinically important source of stone disease in children, accounting for 6% to 8% of pediatric urinary calculi.48 , 55 In their series of cystinuric patients during a 14-year follow-up, Linari et al43 showed that stone disease occurred at a rate of 1.22 stone episodes per patient per year; therefore, the majority of cystinurics will suffer recurrent stone disease during their lifetimes.
Much attention has been directed toward improved means of diagnosis, prevention, and treatment of patients with cystine lithiasis, and current treatment strategies of cystine calculi may entail a multimodal approach. Advances in minimally invasive stone destruction and chemoprevention have given the urologist a sophisticated and often challenging armamentarium in the treatment of these patients. This article reviews the relevant pathophysiology of cystine calculus disease as well as techniques used in its diagnosis. Current medical and surgical techniques used in prevention and treatment also are reviewed.
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Address reprint requests to Martin I. Resnick, MD, Department of Urology, University Hospitals of Cleveland, 11100 Euclid Avenue, Cleveland, OH 44106–5046 |
Vol 24 - N° 1
P. 163-171 - février 1997 Retour au numéroBienvenue sur EM-consulte, la référence des professionnels de santé.
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