Marathon Running Tied to Short-Term Kidney Injury

Marcia Frellick

March 31, 2017

A study of 22 runners in the 2015 Hartford (Connecticut) Marathon found that most temporarily developed acute kidney injury (AKI) directly after the race.

Blood creatinine and urine albumin levels rose after the marathon and pushed 82% of the runners to at least stage 1 AKI, a condition in which the kidneys fail to filter waste from the blood. Microscopy analysis showed that 73% had urine sediments that indicated acute tubular injury.

While the runners studied fully recovered from the kidney injury 2 days after the event, the authors say the study raises questions about the long-term effects for regular marathon runners, especially in warmer climates.

Sherry G. Mansour, DO, from the Program of Applied Translational Research, Department of Medicine, and Section of Nephrology at Yale University School of Medicine in New Haven, Connecticut, and colleagues, published their findings online March 28 in the American Journal of Kidney Disease.

"The kidney responds to the physical stress of marathon running as if it's injured, in a way that's similar to what happens in hospitalized patients when the kidney is affected by medical and surgical complications," senior author, Chirag R. Parikh, MD, PhD, also from Yale Nephrology, as well as the Veterans Affairs Connecticut Healthcare System, said in a press release.

Study participants were seasoned runners (44% men) ranging in age from 22 to 63 years (mean age, 44 years).Requirements for study participation included a body mass index of 18.5 to 24.9 kg/m2 and a minimum 15-mile-per-week training average for the past 3 years.

Among exclusion criteria were any major running injuries in the last 4 months, participation in another marathon in the 4 weeks before the Hartford race, and use of nonsteroidal anti-inflammatory drugs within 2 days before or 1 day after the marathon.

The researchers collected samples 24 hours before the marathon, immediately after, and 24 hours after. In addition to serum creatinine and creatine kinase and urine albumin, the researchers looked at several urine markers of injury (eg, interleukin-6 and interleukin-18) and repair (eg, YKL-40).  They also used a novel urinary biomarker called neutrophil gelatinase-associated lipocalin (NGAL), which has been identified as signaling AKI.

Because the study sample was small, the researchers say, they can only speculate that marathoners adapt well to injury, as evidenced by the temporary AKI.

"This is despite 23% of runners in our cohort having NGAL levels .90 ng/mL, which approach levels traditionally seen in critically ill patients such as those with hepatorenal syndrome or those immediately following cardiac surgery," they write.

The authors also speculate that increase in core body temperature, system inflammation, dehydration, and reduced flow of blood to the kidneys may be behind AKI in marathon runners.

Links to marathon running and kidney function have not been well studied, the authors report, but its relevance is growing with marathons' rise in popularity — 550,600 participants in the United States in 2014.

"The results of our study should be validated in larger cohorts with longer follow-up of kidney function," they conclude.

Dr Parikh added, "Research has shown there are also changes in heart function associated with marathon running. Our study adds to the story — even the kidney responds to marathon-related stress."

The study was supported by the Quinnipiac University Faculty Scholarship grant, the National Institute of Diabetes and Digestive and Kidney Diseases, and the National Institutes of Health. The authors have disclosed no relevant financial relationships.

Am J Kidney Dis. Published online March 28, 2017. Abstract

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