Kidney stones signal poor renal prognosis

By Sally Robertson, B.Sc.Sep 5 2012

People who develop kidney stones may be at an increased risk for developing serious kidney disease later in life, report researchers.

In an analysis of data available for more than 3 million people in Alberta, even a single kidney stone episode increased the likelihood of adverse renal outcomes including kidney failure, report Marcello Tonelli (University of Alberta, Edmonton, Canada) and colleagues in the BMJ.

Using the Alberta Kidney Disease Network, Tonelli et al analyzed physician claims, facility utilization and International Classification of Diseases codes to identify presentations of kidney stones in 1,954,836 individuals over a median follow-up period of 11 years.

They found that that 5333 (0.2%) individuals developed ESRD, 68,525 (4%) developed stage 3b-5 chronic kidney disease, and 6581 (0.3%) had sustained doubling of serum creatinine from baseline levels.

Cox proportional hazard modeling showed that patients who had experienced one or more kidney stones were at 2.16-fold greater risk for incident ESRD than patients who had not experienced any such episodes.

Similarly, one or more kidney stone episodes increased the risk for new stage 3b-5 chronic kidney disease 1.74-fold and for sustained doubling of creatinine concentration, the risk was almost doubled.

The increased risk for these adverse renal outcomes was of a greater magnitude among women than among men, and in those aged under 50 years than in older individuals, notes the team.

However, the risk for all three adverse outcomes was significantly higher among those who had experienced at least one episode of kidney stones compared with those who had not, regardless of gender or age.

The team says the association between kidney stones and progressive loss of kidney function may be the direct result of progressive calcification within the renal interstitium, and specifically, at the tubular basement membrane and around the ducts of Bellini.

"Extension of such calcification into the tubular lumen might cause more renal damage, with potential for progressive scarring, chronic kidney disease, and ultimately ESRD," explain Tonelli et al.

The team says the findings suggest that kidney stones are an important potential contributor to the risk for ESRD and that patients with prior kidney stones should be considered at an increased risk for adverse renal outcomes - especially younger women or those with multiple symptomatic episodes.

"Further research should be aimed at determining the mechanisms explaining this association and assessing the optimal way to prevent kidney stones in the general population," the researchers conclude.

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