Consider the Kidney: An Interview with Mark Perazella, Medical Director for Yale PA Online

Dr. Mark Perazella, medical director of the Yale School of Medicine Physician Assistant Online Program and the Yale Physician Associate Program, is researching a health issue of growing importance: the impact of intense exercise on the kidneys. Perazella senses that “with more people doing more strenuous things like ultramarathons, kidney injury is happening more often.”

When the damage involves athletic teams, there is often media coverage drawing attention to the issue. This occurred, for example, in August 2016, when eight volleyball players from Texas Woman’s University were hospitalized after intense workouts and, again, in January 2017, when three University of Oregon football players were hospitalized after a series of strenuous practices. In both cases, the athletes were diagnosed with rhabdomyolysis, a condition that occurs when there is an injury to skeletal muscle. When muscle is damaged, a protein called myoglobin is released into the bloodstream and then filtered out of the body by the kidneys. Myoglobin breaks down into substances that can harm the kidneys. While many endurance athletes are cognizant of the connection between exercise and the heart, Perazella points out that “[n]obody thinks about their kidneys until they get something like rhabdomyolysis.”

Perazella, a nephrology expert, who, among his other responsibilities, also serves as medical director for the Acute Dialysis Unit in Yale-New Haven Hospital, has played a key role in the launch of the Yale PA Online Program. Students had the chance to meet him during their first immersion on the Yale campus. And, importantly, he was part of the admissions team that admitted them into the program. As medical director, Perazella also is responsible for reviewing and approving the curriculum for the PA Online Program.

“Nobody thinks about their kidneys until they get something like rhabdomyolysis.”

—Dr. Mark Perazella, Medical Director, Yale PA Online Program

Recognizing that incidents of high intensity exercise were leading to physical harm, Perazella wanted to know at what point exercise goes from helpful to harmful and why. He used the 2015 Hartford Marathon, less than an hour’s drive from the Yale campus, as a data resource. Perazella and a team of researchers persuaded 22 runners to allow them to take blood and urine samples just before, and immediately after, they pushed their bodies to extremes. The runners were hard-core athletes with no serious health issues. Each had averaged training runs of at least 15 miles every week for three years. They were precisely the type of runner one would expect to do well running 26.2 miles.

Yet the researchers found that 18 of the 22 runners showed signs of acute kidney injury shortly after the race, posting levels of a particular biomarker on par with critically ill patients who had experienced intensive surgeries or significant trauma. The runners, however, said they didn’t feel ill.

“What we saw in the runners suggested kidney injury,” Perazella said. “But 48 hours later, all of these things were back to normal. It was a transient injury.” While acute kidney damage is typically based on the decline in urine output or a rise in serum creatinine levels, such indicators are only a temporary problem in people who have recently engaged in intense exercise.

What the researchers saw in the marathon runners was different in scale than the severe, obvious kidney damage observed in other settings like the ICU, and in athletes who are diagnosed with rhabdomyolysis. “But it suggests that excessive exercise is associated with this subtle kidney injury,” Perazella said.

More research is needed to determine exactly why a kidney injury that does not rise to the level of rhabdomyolysis occurs. But experts have learned that heat stress and dehydration can reduce blood flow to the kidneys and cause mild, temporary injury. Researchers also know that taking nonsteroidal anti-inflammatory drugs (NSAIDs), including over-the-counter painkillers like ibuprofen and naproxen, can impair kidney function if ingested just before or after hard workouts.

The long-term effect of intense exercise on the kidneys remains an unknown. Further research is needed to determine if the damage is fleeting or if repeated injuries pile up over a lifetime.

Citation for this content: Yale School of Medicine Physician Assistant Online Program