Persistent decline in renal function seen after first stone case

Researchers studying the relationship between kidney stones and chronic kidney disease have discovered evidence of kidney disease after the first stone event.

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In a paper published online in Mayo Clinic Proceedings (Oct. 21, 2016), nephrologists revealed a persistent decline in kidney function following a patient’s initial case of kidney stones.

“Stone formers only have a transient rise in serum creatinine, but they have a sustained higher cystatin C and urine protein after the first stone event. This means that some, but not all markers of kidney function show abnormalities after the first stone event,” co-lead author Andrew Rule, MD, told Urology Times.

According to the National Kidney Foundation, kidney stones affect approximately 8.8% of adults, a number that has been rising for years. Previous studies on the subject have identified a long-term risk of chronic kidney disease in stone formers. However, prior research has not assessed kidney function immediately after a first stone event.

“We and others have known that stone formers have about twice the risk of kidney failure as controls. We wanted to know if there was any evidence of kidney disease after the first stone event. We did not expect there to be any sustained kidney function abnormalities after the first stone event because we thought kidney dysfunction would only occur after multiple stone events,” Dr. Rule said.

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For the study, the authors looked at 384 first-time stone formers with study visits 90 days and 180 days after the stone event. Clinical and laboratory characteristics at visit 1 were compared between stone formers and controls using linear and logistic regression models with adjustment for age and sex. Kidney function by serum creatinine, cystatin C, 24-hour urine protein, and 24-hour urine albumin levels were compared between stone formers and controls at visits 1 and 2 using age- and sex-adjusted and multivariable-adjusted linear and logistic regression models.

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The results of the research were matched to 457 controls. When compared to the control group, kidney stone formers maintained higher levels of the blood marker cystatin C and higher levels of urine protein―both of which are connected with higher risk of chronic kidney disease. Even when other risk factors were added to the study-including urine chemistries, hypertension, and obesity-those with a kidney stone episode were still found to possess subsequent abnormal kidney function.

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“Our research shows that the implications of kidney stones may go beyond the discomfort they are so often associated with. Prevention of kidney stones may be beneficial for a person’s overall kidney health,” Dr. Rule said.

The findings, Dr. Rule noted, will help doctors better understand the long-term implications of kidney stones beyond recovery time.

“Long-term follow-up of the cohort will allow us to assess whether these kidney function abnormalities are predictive of more clinically evident chronic kidney disease. The usual concern with kidney stones is their painful recurrence, but stone formers are also at risk for other diseases, including chronic kidney disease,” Dr. Rule said.

The Mayo Clinic research team also consisted of co-lead author William Haley, MD; Felicity Enders, PhD; Lisa Vaughan, MS; Ramila Mehta, MS; Maxton Thoman, BS; Terri Vrtiska, MD; Amy Krambeck, MD; and John Lieske, MD.

More on Stone Disease:

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