Reasons for Having One Kidney
There are a number of different reasons why somebody would have only one functioning kidney:- Birth Defect: Some people are born missing one kidney (renal agenesis) or with an underdeveloped and non-functioning kidney (renal hypoplasia). It is estimated to occur once every 1000 births.
- Surgical Removal: There are a number of reasons why somebody might have a kidney removed but the most common are: kidney donation, injury, cancer, and infection.
- Kidney Transplantation: People who have received a kidney transplant are considered to have one kidney because their two native kidneys are non-functional.
- Kidney Disease: Most kidney diseases involve both kidneys at once. However, certain diseases can affect only kidney only by involving blood vessels (ie. atherosclerosis) or the ureter (ie. kidney stones).
Consequences of Having One Kidney
Because one kidney can perform the job of two, the long term prognosis of having a solitary kidney is very good. However, longterm follow-up studies of people with only one kidney have identified areas of concern:- High Blood Pressure: Many people with one kidney experience a slightly higher than normal rise in their blood pressure. This rise is relatively modest and often easily treated.
- Decreased Kidney Function: The remaining kidney tries to make up for the reduced kidney function caused by having only one kidney. This compensation isn’t usually 100% so there is usually a reduction in GFR. In the absence of kidney disease and stable kidney function, it is not usually a problem.
- Protein in Urine: Having one kidney can lead to some mild loss of protein in the urine, but it is not a sign of serious kidney disease.
Important Precautions
Most people with a solitary kidney do very well but if something happens to that kidney, it can be a big problem. To help protect the this kidney, there are a few precautions you need to consider:- Limiting Protein: Some people talk of limiting your protein intake, but unless you are truly eating an excessive amount or your kidney function is poor, it is not usually absolutely indicated.
- Checking Blood Pressure: Controlling high blood pressure is extremely important because of the damage it can cause kidneys. Your blood pressure should be checked every 6-12 months at the minimum (more if it high).
- Screening for Kidney Disease: When it comes to identifying kidney disease in someone with reduced kidney function, sooner the better. This means periodically checking for protein in the urine and monitoring kidney function with an estimated GFR.
- Avoid Injury: Protecting your remaining kidney is very important. This means avoiding medications and toxins known to harm the kidney as well as trauma and other physical injury. Protecting against trauma is particularly important for people whose kidney is not well protected (ie. ectopic kidney, horseshoe kidney, kidney transplant).
Participating in Sports
The most common cause of kidney injury from trauma is due to motor vehicle accidents and penetrating wounds. However, many doctors would rather err on the side of caution and recommend avoiding sports with heavy contact or collision such as:- Boxing, wrestling, lacrosse, body building, rodeo, and martial arts
- Football, soccer, basketball, hockey, diving, and water polo
- Bike riding, Skate boarding, inline skating, and snowboarding
Because the kidneys are less protected by the ribs in children, there is an increased risk of kidney trauma. However, when compared to motor vehicle accidents and penetrating wounds, the risk of participating in sports is substantially less. At the present time, there is no consensus on whether children with a solitary kidney should participate in sports or not.
- The 2001 American Academy of Pediatrics Guidelines on Medical Conditions affecting sports participation recommends those with a solitary kidney receive “individual assessment prior to participation in contact, collision, or limited-contact sports.”
- Despite the lack of consensus and the relatively low rate of kidney injury during sports, most pediatric urologists will nonetheless recommend avoiding contact sports. However, with proper protective gear and clear understanding of the risks, approval for certain sports may be possible.
Sources
- Solitary Kidney. National Kidney and Urologic Diseases Information Clearinghouse [online]. Accessed August 18, 2006.
- Living With One Kidney. National Kidney Foundation [online]. Accessed August 18, 2006.
- Medical Conditions Affecting Sports Participation. American Academy of Pediatrics [online]. Accessed August 18, 2006.