Adequacy of a Single 24-Hour Urine Collection for Metabolic Evaluation of Recurrent Nephrolithiasis
ABSTRACT There is much debate about whether 1 or 2, 24-hour urinalyses are adequate for metabolic evaluation of stone formers. We determined whether repeat 24-hour urine collection provides information similar to that of the initial 24-hour urine collection and whether repeat collection is necessary.
We analyzed 2, 24-hour urine collections in 777 patients obtained from 2001 to 2005. Samples were collected 3 days or less apart before pharmacological intervention and analyzed elsewhere for routine stone risk profiles of urine calcium, oxalate, citrate, uric acid, sodium, potassium, magnesium, phosphorus, ammonium, chloride, urea nitrogen and creatinine.
No parameters showed a statistically significant difference between 24-hour urine samples 1 and 2 when mean values were compared (pairwise t test each p >0.05, range 0.06 to 0.87). Using Pearson's correlation all parameters showed positive correlation coefficients (r = 0.68 to 0.89, each p <0.0001). The mean of individual patient differences in samples 1 and 2 were compared to 0 and 6 of 12 showed no difference (p >0.05) while for the remaining 6 p value was <0.05. The percent difference was 0.5% to 4.19% for all urinary parameters.
One 24-hour urine sample is sufficient for metabolic evaluation of recurrent stone disease. There is no significant difference in 12 urinary parameters between 24-hour urine samples collected within 3 days of each other. This information is useful to providers and may decrease patient inconvenience and the overall cost of metabolic stone evaluation.
- [Show abstract] [Hide abstract]
ABSTRACT: Office management of stone disease is an important component of a urologist's practice. Evaluation should include analysis of stone composition, 24-hour urine studies, identification of modifiable risk factors, and targeted dietary, lifestyle, and/or medical therapy. A sizeable portion of investigated etiologies and risk factors for stone disease have centered on the complex interplay between obesity, diabetes, and other disease states that comprise the metabolic syndrome. Alternatives to traditional preventive therapy, such as probiotics and various fruit juices, are still being studied but may prove useful adjuncts to traditional preventive therapy, where the mainstays remain increased fluid intake, dietary modification, and pharmacologic therapy. Future studies on preventive therapy of urolithiasis are likely to focus on strategies to increase compliance, cost-effectiveness, and systems-based implementation.Current Urology Reports 06/2013; DOI:10.1007/s11934-013-0347-4
- [Show abstract] [Hide abstract]
ABSTRACT: Purpose: To determine whether 1 versus 2, 24-hour urine collections is optimal in the metabolic evaluation of nephrolithiasis. Methods: We retrospectively reviewed all 24-hour urine collections performed at our tertiary stone clinic from July 1997 to February 2012. We identified patients with 2, 24-urine collections performed within 10 days of each other. Samples were analyzed by an outside laboratory for the standard urinary parameters. For each parameter, pairwise t-tests were performed and Pearson's correlation coefficients were calculated to compare samples 1 and 2. Additionally, the number of cases that changed from normal to abnormal or vice versa was also evaluated for each parameter and the Kappa statistic was calculated. Results: A total of 813 subjects submitted 2, 24-hour urine collections within 10 days. Mean age was 53.2 years and mean BMI was 28.8 kg/m2. Based on Cr 24/kg, subset analysis was performed for all properly collected samples (n=236). Using pairwise t-test, 24-hour urine volume (p=0.0365) and phosphorus (p=0.0387) showed a statistically significant difference between samples 1 and 2. None of the other urinary parameters demonstrated a statistically significant difference when means were compared (pairwise t-test, p>0.05), (range 0.061-0.9983). Pearson's correlation demonstrated a high degree of correlation between 2, 24-hour urines for all variables (r = 0.66 to 0.95, each p <0.0001). However, depending on the urinary parameter assessed, 5.5% to 44.9% of patients changed from normalcy to abnormality, or vice versa. Conclusions: A single 24-hour urine collection may have changed clinical decision making up to 45% of patients. Therefore, we recommend 2 collections to optimize the diagnostic yield and appropriately target stone prevention strategies.Journal of endourology / Endourological Society 09/2012; 27(3). DOI:10.1089/end.2012.0216 · 1.75 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: To describe the metabolic risk factors and investigate the effect of prophylaxis based on these factors on long-term recurrence of urolithiasis in pediatric patients with hypocitraturia. One-hundred and twenty-nine pediatric patients who underwent percutaneous nephrolithotomy between January 2008 and June 2011 were evaluated for metabolic risk factors. The patients with hypocitraturia were enrolled in this study and the data were analyzed using statistical methods for a mean period of 2 years for metabolic abnormalities, stone type, and the effect of potassium citrate prophylaxis on stone recurrence. A 24-h urine metabolite analysis revealed one or more metabolic risk factors in 115 (89.2 %) of the patients, whereas 14 (10.8 %) of the patients had no metabolic abnormalities. Eighty-two (63.5 %) of 129 patients had hypocitraturia. Of them, 43 (52 %) were male and 39 (48 %) were female, with a mean age of 9.7 ± 4.9 and 6.7 ± 4.4 (1-16) years, respectively(p = 0.102). Thirty-five (42.7 %) had pure hypocitraturia, and 47 (57.3 %) had two or more metabolic abnormalities. The most common dual metabolic abnormality was hypocitraturia and hypomagnesuria. Seventy-one patients (87 %) with hypocitraturia received medical prophylaxis and continued regularly, whereas 11 (13 %) patients did not receive medical prophylaxis despite being advised to do so. After a mean follow-up of 26.5 ± 9.4 months, the rate of recurrence was 1.4 % in the patients with hypocitraturia who continued prophylaxis and occurred in all of the patients who did not receive prophylaxis (p < 0.001). Calcium oxalate stones (95.2 %) were the most commonly found stones in the stone analysis. Detailed clinical and laboratory evaluations should be performed in children with urolithiasis. Appropriate prophylactic treatment as potassium citrate, should be given to prevent reformation of stones in patient with hypocitraturia.02/2013; 41(1):9-13. DOI:10.1007/s00240-012-0539-2