Evaluation of Biochemical Risk Factors and Relative Supersaturation in Patients with Recurrent Nephrolithiasis / 대한신장학회잡지

PURPOSE: We examined a 24-h urine to evaluate the important biochemical risk factors and relative supersaturation in patients with recurrent nephrolithiasis. METHODS: A total of 17 patients with recurrent nephrolithiasis were analyzed for urinary biochernical stone risk factors and relative supersaturation. They were evaluated using a single 24-h urine specimen with StoneRisk(R) Diagnostic Profile on a random diet. Urinary stone risk factors are calcium, oxalate, citrate, magnesium, uric acid, pH, 24-h urine volume, sodium, phosphorous. Relative supersaturation with respect to stone-forming salts such as calcium oxalate, brushite, monosodium urate and uric acid were calculated. These factors were classified one or more etiologic categories in each patient. RESULTS: Of 17 patients 16 patients (94.2%) had abnormal urinary biochemistry that placed them into one or more of 15 etiologic categories. A single abnormality was documented in only one patient. One patient had no diagnostic abnormality. High urinary sodium encountered in 13 (76.5%) of the patients. Hypercalciuria and hyperuricosuria accounted for 9 (52.9%) and 7(41.1%) of the patients, respectively. The acquired problem of low urine volume (< 2L/d) was found in 8 (47.1%) of the patients and hypoci-traturia affected in 4 (23.5%). But hypomagnesiuria was not detected. The relative supersaturation with respect to monosodium urate was highest and increased in 70.6Yo of patients. CONCLUSION: The StoneRisk(R) Diagnostic Profile using a single 24-h urine specimen is a very useful tool not only in detecting metabolic, environmental and physicochemical abnormalities but also in providing specific therapeutic or preventive guidelines of patients with recurrent nephrolithiasis. In our study the most important biochemical risk factor of recurrent stone former is a high urinary sodium. Furthermore, there is a distinct evidence of high relative supersaturation with respect to monosodium urate. High sodium intake is probably the most important risk factor in patient who develop recurrent stone formation. Therefore, dietary sodium restriction would reduce probability of recurrent nephrolithiasis.

Interpretative Reporting System of the Analysis of Urine Stone Risk / 대한임상병리학회지

BACKGROUNDS: Metabolic and environmental evaluation can provide a powerful tool for management of patients with urolithiasis. We developed the interpretative reporting system of the analysis of urine stone risk and evaluated the clinical usefulness of this system. METHODS: The analysis of urine stone risk with thirty five cases were performed at Samsung Medical Center from January 1 to June 30, 1999. They were studied using a protocol based on 24 hour urine tests including volume, pH, sodium, potassium, chloride, calcium, phosphate, uric acid, magnesium, citrate, oxalate, ammonium and creatinine. Nitroprusside-cyanide spot test, routine urine analysis, urine culture, and several serum tests including electrolytes, calcium, phosphate, uric acid, creatinine, alkaline phosphatase, parathyroid hormone were also included. The results of physical and chemical analysis of urine stone were considered together. Relative supersaturations were estimated using software program EQUIL. We provided comprehensive interpretation about the specific causes and risks of stone formation in each patient. RESULTS: Hyperoxaluria (57.1%), hypercalciuria (57.1%), natriuresis (51.4%) and hypocitraturia (34.3%) were commonly found at the urine of patients with urolithiasis. The results of urine stone risk analysis based on relative supersaturation and related laboratory findings correlated well with the results of urine stone analysis. Mixed form of calcium oxalate stone was most commonly encounterd. Increased supersaturation with respect to calcium oxalate stone was noted in 23 cases (65.7%), which were frequently accompanied by hyperuricosuria or increased supersaturation with uric acid stone. The pH of urine was generally increased in struvite stones and decreased in uric acid stones. CONCLUSIONS: Analysis of urine composition and determination of urine stone risk were very useful for evaluation of patients with urolithiasis. And the interpretative reporting system of the analysis of urine stone risk can provide meaningful information in the treament and prevention of stone disease.