24-Hour Urine Collection for Pediatric Stone Formers: Is it Worth it?
Kevin Carnes, MD, Adam S. Howe, MD, Paul Feustel, Ph.D., Mark White, MD, Barry A. Kogan, MD.
Albany Medical College, Albany, NY, USA.
BACKGROUND: The incidence of nephrolithiasis in children is increasing and is now 50 per 100,000 adolescents in the US. The AUA guidelines state one or two 24-hour urine collections should be performed for motivated first-time stone formers and given that children have a lifetime for potential recurrences metabolic work-up has been recommended. Yet 24-hour urine collections can be problematic, especially in children. We sought to study the benefits of 24-hour urine collections in children with stones.
METHODS: We performed a single center, retrospective chart review of all pediatric nephrolithiasis patients < 18 years of age at Albany Medical Center who supplied a 24-hour urine collection between 8/2000 and 10/2018. Standard recommendations for all patients included reducing salt intake, increasing fruits/vegetables, normal calcium intake, restricting animal protein and oxalate, and increasing fluids, especially those containing citrus. We assessed the 24-hour urine results for abnormalities and then for whether the results lead to a change in management.
RESULTS: Seventy pediatric nephrolithiasis patients who had 24-hour urine collection were reviewed. Recommendations other than standard dietary and fluid intake changes were made in 8/70 (11%). One was placed on dietary dairy/calcium restriction, two were placed on hydrochlorothiazide and 7 on potassium citrate. A low citrate/calcium ratio (327 vs. 525, p < 0.03) and whether the test was ordered by nephrology vs. urology (26% vs. 2%, p < 0.003)) were predictive of an additional recommendation. Of the 8 patients who had changes recommended only 1/8 had a repeated 24-hour urine collection, 3/8 never followed up and 2/8 stopped the medicines prior to follow up. 55% of the studies were incorrectly collected, and total costs are estimated between $9,800 and $28,000.
CONCLUSIONS: 24-hour urine collection for first time pediatric stone formers is expensive, difficulty to accomplish and infrequently leads to treatment changes. Our data suggest it is unnecessary.
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