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Health Issues

Children Born With One Kidney

Most people are born with two kidneys. However, as many as 1 in 1,000 people are born with only one kidney. Usually, children with one kidney are perfectly healthy. However, they do require monitoring to keep their one (single) kidney healthy.

Why are some people born with only one kidney?

For most people born with one kidney, we do not know why it happens. In a small number of people, being born with one kidney is part of a syndrome. A syndrome means that the child is born with more than one health problem.

In the past, many parents did not even know their child had only one kidney. But today, most pregnant women have an ultrasound evaluation of their baby, so most infants with one kidney are discovered before they are born.

Other infants are born with two kidneys but have only one healthy kidney because the other kidney did not develop correctly before birth. For other people born with two kidneys, one kidney may be damaged or removed due to an accident, tumor, infections, or (in adults) kidney donation for a kidney transplant.

Is it genetic?

For most families of a child with one kidney, the risk of a second child with a similar problem is very low. But this should be discussed with your pediatrician or obstetrician, who may refer you to a genetic counselor.

What are the long-term issues for someone with one kidney?

Most people born with one kidney lead full and normal lives. This is why a person with two healthy kidneys can donate one kidney to a person with kidney failure. In a child, a healthy, well-formed single kidney typically grows faster and becomes larger than if the kidney was one of a pair of kidneys. This extra growth is good and helps the single kidney do the work of two kidneys.

Your child's pediatrician will perform tests to determine if a single kidney is healthy. These may include:

  • Blood and urine tests to see how well the kidney is working

  • Imaging studies such as an ultrasound to make sure the kidney looks normal and that the urine drains normally

Importance of blood pressure & urine checks

Some people with a single kidney may develop health problems later in life, such as high blood pressure or protein leaking from the kidney into the urine. Protein in the urine can be a sign of stress on the kidney's filters, and ongoing leakage of large amounts of protein from the kidneys can also cause kidney problems, but this can be controlled. The American Academy of Pediatrics (AAP) recommends yearly screening of children for high blood pressure at their primary care doctor's office. It is reasonable to screen children and adults with a single kidney for protein in the urine.

Is it OK for a child with one kidney to play sports?

Fortunately, the kidneys are located deep in the body and are less likely to be injured than the brain, neck, spleen or liver.

The AAP recommends that children and adolescents with a single kidney be allowed to play most sports. This decision, however, should be based on several factors:

  • Advice of your pediatrician, pediatric urologist or pediatric nephrologist

  • Health of the single kidney

  • Current heath of your child

  • Sport in which they are participating

  • Position they would play

  • Level of competition

  • Relative risk of severe injury

In the past, physicians cautioned against contact or collision sports (where intentional contact is expected). However, studies show that the risk of sustaining a kidney injury from football or wrestling is actually quite low. This is why the overall health and wellbeing of the child deserves a discussion with their doctor. Padding designed specifically to protect the kidney should also be considered when making this decision, although little is known about its effectiveness.

What can parents of a child with one kidney do to keep them healthy?

Children with a one kidney can lead a normal, healthy life. They do not need special diets if the kidney is working well. They should have regular well-child care as recommended by the AAP, including blood pressure measurement. Your doctor may want to screen your child for protein in the urine.

More information

Last Updated
American Academy of Pediatrics, American Society of Pediatric Nephrology and the National Kidney Foundation Patient Education Collaborative (Copyright © 2022)
The information contained on this Web site should not be used as a substitute for the medical care and advice of your pediatrician. There may be variations in treatment that your pediatrician may recommend based on individual facts and circumstances.
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