Background

The kidneys are a vital organ, located in the right and left abdominal flanks, and sit behind and below the rib cage. The kidneys clean wasted from the body’s blood, which is then flushed out as urine.

Kidneys are the third-most common abdominal organs injured. In sports, kidneys are typically injured when someone is hit in the area of the kidneys (blunt trauma) or from intense exercise. Blunt trauma can cause as a bruise (contusion) or cut (laceration) to the kidney and is more common in children.

Trauma is usually from a collision, like falling off a bike, or from contact sports like football, hockey and boxing. The cause of exercise-induced kidney injury is not fully understood, but it happens more commonly during intense and prolonged exercise seen in people like military recruits and marathon runners.

Symptoms/Risks

Symptoms of kidney injury can be none, mild, or severe depending on the injury. An athlete with severe kidney injury from trauma may present with nausea, vomiting, abdominal or flank pain and bruising, and low blood pressure from blood loss.

An athlete with exercise-induced injury may have no symptoms or find blood (hematuria) or extra protein (proteinuria) in their urine. Many people with exercise-induced kidney injury often have very sore muscles as well from their intense workout.

Sports Medicine Evaluation & Treatment

In a suspected kidney injury, a sports medicine physician will evaluate the athlete by checking vital signs (heart rate and blood pressure) and examining the abdomen and back. Kidney health and function can be checked through blood draw and urine testing (urinalysis). If there is a concern for a more severe injury like a contusion or laceration, a CT (computerized tomography) scan may be recommended along with a visit to the emergency department.

Injury Prevention

Blunt kidney injury is rare in sports, but protective equipment may be helpful, especially if you are born with only one kidney. For exercise-induced kidney injury, staying well hydrated and not performing physical activity the body isn’t use to doing may be helpful.

Return to Play

Returning to play depends on the severity of kidney injury and is usually determined when urine studies (urinalysis) are normal. For the most common blunt kidney injuries, return to play is typically in 2-6 weeks, unless there is a more severe injury that requires surgery.

For exercise-induced kidney injury, urine studies typically improve within 48-72 hours. Return to play from this type of injury depends on many other factors that must be assessed for by the sports medicine physician.

AMSSM Member Authors
Geoffrey Dreher, DO

References
Bernard, J. (2009). Renal Trauma: Evaluation, Management and Return to Play. Current Sports Medicine Reports, 8(2), pp.98-103.
Gerstenbluth, R., Spirnak, J. and Elder, J. (2002). Sports Participation and High Grade Renal Injuries in Children. Journal of Urology, 168(6), pp.2575-2578.
Mansour, S., Verma, G., Pata, R., Martin, T., Perazella, M. and Parikh, C. (2017). Kidney Injury and Repair Biomarkers in Marathon Runners. American Journal of Kidney Diseases, 70(2), pp.252-261.
Viola, T. (2013). Closed Kidney Injury. Clinics in Sports Medicine, 32(2), pp.219-227.