New Study Reveals Unexpected Kidney Damage Among Marathon Runners

Do you love running marathons to keep fit? A recent study suggests that your kidneys might not be functioning as smoothly as you’d expect.

A study published in the American Journal of Kidney Diseases found that over 80% of runners who completed the 2015 Hartford Marathon in Connecticut exhibited signs of acute kidney injury (AKI), a condition linked to symptoms such as nausea, dehydration, elevated blood pressure, and potentially life-threatening complications.

The kidneys are responsible for filtering blood, generating urine, and producing hormones that regulate blood pressure and maintain bone health. AKI, often triggered by diminished blood flow to the kidneys, leads to the accumulation of waste products like salt and chemicals in the bloodstream, disrupting fluid balance. Intense physical stress, such as running a marathon (26.2 miles or 42 kilometers), can cause kidney function to decline rapidly within hours or days.

Muscle activity naturally produces the waste product creatinine. Elevated blood creatinine levels and reduced urination can signal impaired kidney function. Researchers measured creatinine and urine levels in runners 24 hours before the marathon, right after finishing, and 24 hours post-race. For 82% of participants, creatinine levels rose to stages 1 and 2 of AKI, as defined by the Acute Kidney Injury Network, indicating up to a threefold increase from baseline. Additionally, 73% of runners exhibited tubular injury, a condition damaging kidney structures that can lead to acute kidney failure.

This study is preliminary, so don’t let the findings discourage you. Out of over 1,900 finishers at the Hartford Marathon, only 22 runners (average age 44, 9% male) were included in the research.

Marathon runners may develop AKI due to elevated body temperatures and dehydration. However, AKI symptoms in the tested runners resolved within two days. Before you consider quitting running, remember that further research is needed to determine if marathoners are at significant risk of kidney disease.