Uric Acid Calculi Associated with Ileostomy for Ulcerative Colitis

Implications of disorders of purine metabolism for the kidney and the urinary tract

The spectrum of kidney and urinary tract disorders related to purines comprises acute hyperuricosuric nephropathy, chronic urate nephropathy and urolithiasis. Two factors in the development of acute hyperuricosuric nephropathy are increased uric acid concentration and low pH in the tubular fluid. Chronic urate nephropathy still possess several problems: incidence (although this seems to be decreasing, presumably owing to effective prevention), the source of interstitial urate, the cause of the interstitial deposition of urate, and the role of urate deposits in the pathogenesis of the interstitial nephropathy. The relation of the experimental nephropathy to the pathogenesis of chronic urate nephropathy in the human is not yet clear but a model is proposed according to which interstitial urate derives from two sources: hyperuricaemic plasma and hyperuricosuric tubular fluid. Urolithiasis related to purines leads to uric acid-urate stones, xanthine stones, 2,8-dihydroxyadenine stones, iatrogenic xanthine and oxipurinol stones, and possibly calcium stones. Pathogenetic factors in uric acid lithiasis are hyperuricosuria (whether due to an inborn enzyme abnormality or of unknown aetiology) and low urinary pH; oliguria is a contributory factor. There remain several open questions about uric acid lithiasis: incidence, the shift of its location from lower to upper urinary tract, the interplay of pathogenetic factors, and the role of compounds which inhibit crystallization.

Metabolic evaluation of stone disease patients: a practical approach

In the last three decades, minimally invasive techniques have progressed significantly, replacing traditional open surgery as the mainstay of stone disease surgical treatment. The challenge for the next millennium remains medical prevention of calcium urolithiasis, a field where less dramatic progress has been achieved during the same period of time. The purpose of this article is to provide the practicing urologist with current practical guidelines for the assessment and management of calcium urolithiasis patients. The recommendations are based on the latest available information regarding the pathogenesis, medical treatment options, and decision-making rationale when managing these challenging patients. Every urolithiasis patient should undergo a basic evaluation, which is considered the minimal essential diagnostic work-up, in order to rule out obvious, treatable systemic causes of urinary stone disease. All patients should be advised about conservative nonspecific preventive measures. High-risk stone patients should have a more extensive metabolic evaluation based on two 24-hour urine samples. Treatment protocols for each patient are tailored individually according to the metabolic evaluation findings.

Prophylaxis of uric acid stone in patients with inflammatory bowel disease following extensive colonic resection

Seven patients (13.0%) among 54 patients with inflammatory bowel disease treated by extensive colonic resection were complicated by renal stone. The mean urinary pH value in cases complicated by renal stones (5.3 +/- 0.4) was significantly lower than among those without stones (6.1 +/- 0.3, P less than 0.01). Sodium bicarbonate (4 gm/day, q.i.d.) was given to 11 patients with renal stones and/or hematuria, whose urinary pH was lower than 5.0 or whose urinary sediments were positive for uric acid crystals since Oct. 1985. Their urinary pH and Na concentration increased significantly and no renal stone complication has been seen in the treated group.

Prevention of uric acid stone formation by sodium bicarbonate in an ileostomy patient--a case report

A 38 year old female underwent a proctocolectomy and ileostomy for ulcerative colitis in February, 1974. For 8 year post-operatively, she excreted innumerable renal stones, mainly composed of uric acid. Her urine was highly acidic and hyperuricosuric with a low concentration of sodium. Sodium bicarbonate 4 gm/day, t.i.d., was started in October 1985, after which her renal stone excretion completely ceased (up until March, 1987), except for one incidence of stone excretion when she discontinued therapy for a week. During the sodium bicarbonate therapy, her urinary pH and Na concentration were elevated. Furthermore, sodium bicarbonate significantly elevated the urinary pH and Na concentration of other ileostomy patients. Thus, sodium bicarbonate could be used for the possible prophylaxis of uric acid formation in selected ileostomy patients.