Background: It is estimated that one in 1,500 persons is born with a single kidney. Student athletes with a single, normally functioning kidney are often discouraged from participating in contact or collision sports because of the risk of kidney injury. Surveys of physicians show that most would recommend against participation, especially for contact sports. Although the American Academy of Pediatrics gives a “qualified yes” to participation in contact sports, it does not provide specific guidelines for assessment. Because there are few published data describing the risk of kidney injury, Grinsell and colleagues quantified the incidence of sport-related kidney injury among high school athletes.

The Study: The authors used data from the prospectively collected National Athletic Trainers' Association Injury Surveillance Study. Between the academic years 1995 and 1997, certified trainers at 240 U.S. high schools reported athlete-exposures and injuries among varsity athletes in football, wrestling, baseball, field hockey, softball, girls' volleyball, boys' and girls' basketball, and boys' and girls' soccer. Reportable injuries included any fracture or dental injury, and any other injury that prevented return to play that session or the following day. The type of sport, affected body part, and severity of injury were recorded, as well as whether the injury occurred during a practice or competition, the type of medical management required, and return-to-play timelines. Catastrophic kidney injury was defined as an irreversible injury or one requiring surgical removal of the kidney. Athlete-exposures were defined as one student athlete playing any portion of one competition or practice.

Results: During the study, more than 4.4 million athlete-exposures and 23,666 injuries were reported. Injury rates, expressed as per million athlete-exposures, were recorded for kidney, head/neck/spine, neurotrauma (including concussion), knee, eye, and testicle. Of the 18 kidney injuries, three were lacerations and 15 were contusions; most kidney injuries (12) occurred during football. None required surgery or resulted in permanent dysfunction. To put kidney injury rates into perspective, football players had the highest rate of kidney injury (9.2 per million athlete-exposures), but also the highest rate of knee injuries (1,225.7 per million athlete-exposures).

Conclusion: Sports-related kidney trauma is rare. This small risk should not limit participation for student athletes with a single functioning kidney.