Complete Metabolic Evaluation is Indicated after a First Stone Event: Con

Abstract

Opposing Views Complete Metabolic Evaluation is Indicated after a First Stone Event CON A fundamental tenet in medicine is that more testing is not always better. Should we be per- forming 24-hour urine collections as part of a com- plete metabolic evaluation on every stone former? In other words, is the initial evaluation we do for first time stone formers sufficient to rule out pertinent metabolic disorders, and inform and direct dietary/ lifestyle changes to prevent recurrence? There is already a treasure trove of information gained from the initial evaluation with the first time stone former which should not be overlooked. A thorough medical history should elucidate prior urinary tract infections, any component of metabolic syndrome, gastrointestinal diseases and related surgery, relevant medications and familial stone formation. A review of the dietary and occupational history provides insight into dietary and lifestyle habits that contribute towards stone risk. Routine serum chemistry studies, including electrolytes, calcium, creatinine and uric acid, will screen for underlying metabolic disorders including renal tubular acidosis type 1, primary hyperparathyroid- ism, chronic kidney disease and hyperuricosemia. Urinalysis is helpful when high pH and low pH values are extreme, and an infection type of stone can be suspected when infection is present. Imaging will show whether multiple stones are present, overall stone burden and anatomical data. Stone analysis, when available, is sometimes helpful (uric acid, infection, brushite, genetic and drug stones) but less helpful for the majority of calcium based stones. Beyond these tests, there is the complete meta- bolic evaluation, which in current practice is the 24- hour urine collection. Several guideline panels recommend this testing in individuals at high risk for recurrence as determined by the initial eval- uation. 1e3 Interestingly, the AUA (American Uro- logical Association) also recommends metabolic evaluation in interested first time stone formers. 1 Just as not all patients at low risk for prostate cancer need definitive treatment, not all first time kidney stone formers need 24-hour urine collections leading to potential lifelong pharmacologic therapy THE JOURNAL OF UROLOGY ® O 2017 by A MERICAN U ROLOGICAL A SSOCIATION E DUCATION AND R ESEARCH , I NC . and monitoring. Stone recurrence is not guaranteed after the first event, and many first time stone for- mers remain never forma a stone again for the rest of their lives. In contemporary series symptomatic recurrence after the first episode is 30% after 10 years and 39% after 15 years. 4 In the ROKS (Recurrence Of Kidney Stone) nomogram created to predict a second symptomatic stone episode all the risk factors for the model can be extracted from the initial evaluation. 4 No tools exist to predict a second stone event incorporating 24-hour urine collection parameters. Brushing and flossing teeth are most diligently and attentively performed after a dentist visit. And so it goes with provider visits for kidney stones known as the so-called “stone clinic effect.” Multiple pharmacologic intervention trials have demon- strated significant decreases in stone recurrence in the non-intervention groups compared to pretrial rates. 5 For a subset of stone formers, maintaining high fluid intake, reducing salt intake and moder- ating animal protein intake may be enough to pre- vent the second stone event. These interventions are easily prescribed by urologists and primary care providers, achievable, low cost, safe with minimal side effects and good for general health. Perhaps a trial of nonselective dietary interventions is reasonable before proceeding with a 24-hour urine collection. Although we have relied on the 24-hour urine collection to become the “complete” metabolic evaluation there are several limitations to the test. 5 In practice the test often can be more of an art than science to interpret. Its ability to predict recurrence and prognosticate risk is not well established. Collection adequacy has been debated as to whether 1 vs 2 collections are suf- ficient or if urinary creatinine-to-body weight ratio is a reliable indicator of adequacy. Several of the positive pharmacological trials evaluating citrate did not require hypocitraturia, which is also true for several thiazide trials with hyper- calciuria. Rates of urinary metabolic abnormal- ities among first time and recurrent stone http://dx.doi.org/10.1016/j.juro.2016.12.028 Vol. 197, 1-3, March 2017 Printed in U.S.A. www.jurology.com Dochead: Opposing Views DIS 5.4.0 DTD JURO14256_14257_proof 15 December 2016 6:11 pm EO: j