PHILADELPHIA—Injury to the kidneys is rare in high school contact sports, researchers found, calling into question the belief of most physicians that teens with only one kidney should not participate in sports.

Among more than 4.4 million instances in which an athlete participated in a game or practice over the course of two academic years, there were only 18 kidney injuries, according to Matthew Grinsell, MD, PhD, of the University of Utah in Salt Lake City, and colleagues.

None was considered catastrophic, resulted in a known loss of kidney function, or required surgical repair, the researchers reported online ahead of the July issue of Pediatrics.

In comparison, during the same time period, there were 3,450 knee injuries, 2,069 injuries to the head, neck, or spine, 1,219 mild traumatic brain injuries, 148 eye injuries, and 17 testicular injuries.

It has been estimated that one in 1,500 individuals is born with a single kidney and surveys have shown that most physicians restrict participation in contact sports for such patients because of concerns about the consequences of losing that organ: dialysis, transplantation, a reliance on immunosuppressant medications for life, and a greater risk for cardiovascular disease.

But there are few data on the actual risk of sports participation in these patients, and the American Academy of Pediatrics (AAP) has recommended a "qualified yes" for participation pending an assessment of each athlete. The academy does not, however, outline specific criteria that could be used to guide a decision.

Grinsell and colleagues side with the AAP, stating that the findings of the current study "do not support limiting sport participation by athletes with single kidneys."

They did, however, suggest a clarification of the recommendation.

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