The Natural History of Non-Obstructing Asymptomatic Renal Stones

Post on April 16, 2015 by André Broussard, D.C.

April 15, 2015
The Journal of Urology

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  • Asymptomatic, non-obstructing renal calculi are frequently managed expectantly, although there is limited evidence surrounding the natural history of these stones with which to counsel patients. This study identified patients with non-obstructing, asymptomatic renal calculi and retrospectively evaluated the likelihood of de novo symptoms and need for surgical intervention. Approximately one-third of stones resulted in symptoms over a median follow-up of >3 years, with fewer than 20% requiring intervention for pain. While uncommon, asymptomatic obstruction resulting in silent renal deterioration was identified in a small subgroup of patients.
  • These data provide a platform upon which to counsel patients with asymptomatic renal calculi. Certainly, periodic follow-up imaging is required both to identify enlarging stones and to mitigate risk for silent renal loss with asymptomatic obstruction.
    – Matthew Resnick, MD

 

We applaud the effort of Dropkin and colleagues1 for adding to the knowledge of the natural history of asymptomatic renal stones. They performed a retrospective review of non-obstructing asymptomatic renal stones in patients conservatively managed with surveillance imaging. They identified 160 stones with an average size of 7.0 ± 4.2 mm among 110 patients with an average follow-up of 41 ± 19 months. In the study, 28% of the stones caused symptoms and 3% caused silent obstruction necessitating treatment. The only significant predictor for need for intervention was location, with upper-/mid-pole more likely than lower-pole stones to become symptomatic (40.6% vs 24.3%; P = .047) or pass spontaneously (14.5% vs 2.9%; P = .016). The majority of the patients remained asymptomatic through the follow-up period, with 20% requiring surgical intervention once they became symptomatic and 7% spontaneously passing their stones.

Prior studies have found similar progression and intervention rates. Kang and colleagues found that approximately half of patients with asymptomatic renal stones progressed to stone growth or symptomatic disease, with 24.5% requiring surgical intervention.2 Similarly, Koh and colleagues found a 45.9% risk of disease progression with a lower risk of surgical intervention (7.1%),3 while Burgher and colleagues found that larger stone diameter was predictive of progression.4

In the properly counseled patient, conservative management with routine surveillance imaging is an appropriate treatment strategy for asymptomatic non-obstructing renal stones. In our practice, we evaluate patients on a yearly basis with plain film imaging and CT scan as needed to evaluate for metabolic growth or progression to symptomatic disease. These studies highlight the natural progression of incidentally found asymptomatic renal stones, and provide the basis for counseling patients on the risk of disease progression and intervention for those who choose conservative management. It is important to discuss this with patients to clearly define expectations of disease progression and take into account patient preferences when deciding upon the treatment strategy.5

References

  1. Dropkin BM, Moses RA, Sharma D, Pais VM Jr. The natural history of nonobstructing asymptomatic renal stones managed with active surveillance [published online November 15, 2014]. J Urol. doi: 10.1016/j.juro.2014.11.056. http://www.jurology.com/article/S0022-5347%2814%2904902-7/abstract
  2. Kang HW, Lee SK, Kim WT, et al. Natural history of asymptomatic renal stones and prediction of stone related events. J Urol. 2013;189(5):1740-1746. http://www.jurology.com/article/S0022-5347%2812%2905622-4/abstract
  3. Koh LT, Ng FC, Ng KK. Outcomes of long-term follow-up of patients with conservative management of asymptomatic renal calculi. BJU Int. 2012;109(4):622-625. http://onlinelibrary.wiley.com/doi/10.1111/j.1464-410X.2011.10329.x/abstract
  4. Burgher A, Beman M, Holtzman JL, et al. Progression of nephrolithiasis: long-term outcomes with observation of asymptomatic calculi. J Endourol. 2004;18(6):534-539.http://online.liebertpub.com/doi/abs/10.1089/end.2004.18.534
  5. Streeper NM, Sninsky BC, Penniston KL, et al. Patients prefer the use of a patient decision-making aid when discussing surgical options for nephrolithiasis. J Urol. 2014;191(4):e950.http://www.journalacs.org/article/S1072-7515%2814%2900890-4/abstract

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