Kidney Dysplasia: In Infants and Children

• Kidney dysplasia is a condition in which the internal structures of one or both of a fetus’ kidneys do not develop normally while in the womb.
• During normal development, two thin tubes of muscle called ureters grow into the kidneys and branch out to form a network of tiny structures called tubules.
• The tubules collect urine as the fetus grows in the womb.
• In kidney dysplasia, the tubules fail to branch out completely.
• Urine that would normally flow through the tubules has nowhere to go.
• Urine collects inside the affected kidney and forms fluid-filled sacs called cysts.
• The cysts replace normal kidney tissue and prevent the kidney from functioning.
• Kidney dysplasia can affect one kidney or both kidneys.
• Babies with severe kidney dysplasia affecting both kidneys generally do not survive birth.
• Those who do survive may need the following early in life:
  • blood-filtering treatments called dialysis
  • a kidney transplant
• Children with dysplasia in only one kidney have normal kidney function if the other kidney is unaffected. Those with mild dysplasia of both kidneys may not need dialysis or a kidney transplant for several years.
• Kidney dysplasia is also called renal dysplasia or multicystic dysplastic kidney.
• Kidney dysplasia is a common condition. Scientists estimate that kidney dysplasia affects about one in 4,000 babies.1 This estimate may be low because some people with kidney dysplasia are never diagnosed with the condition. About half of the babies diagnosed with this condition have other urinary tract defects.
• Babies who are more likely to develop kidney dysplasia include those those parents have the genetic traits for the condition with certain genetic syndromes affecting multiple body systems whose mothers used certain prescription medications or illegal drugs during pregnancy.

• The kidneys are two bean-shaped organs, each about the size of a fist.
• They are located just below the rib cage, one on each side of the spine.
• Every day, the two kidneys filter about 120 to 150 quarts of blood to produce about 1 to 2 quarts of urine, which is composed of wastes and extra fluid. Children produce less urine than adults - the amount they produce depends on their age.
• The urine flows from the kidneys to the bladder through the two ureters, one on each side of the bladder.
• The bladder stores urine.
• The muscles of the bladder wall remain relaxed while the bladder fills with urine. As the bladder fills to capacity, signals sent to the brain tell a person to find a toilet soon.
• When the bladder empties, urine flows out of the body through a tube called the urethra, located at the bottom of the bladder.

A baby with kidney dysplasia might have other urinary problems that affect the normal kidney. On the left, urine is blocked from draining out of the kidney. On the right, urine flows backward from the bladder into the ureter and kidney, a condition called reflux.

Many babies with kidney dysplasia in only one kidney have no signs of the condition.

• In some patients, the affected kidney may be enlarged at birth and may cause pain.
• The affected kidney may be enlarged at birth.
• Abnormalities in the urinary tract may lead to urinary tract infections.
• Children with kidney dysplasia may develop high blood pressure, but only rarely.
• Children with kidney dysplasia may have a slightly increased risk for kidney cancer.
• Chronic kidney disease and kidney failure may develop if the child has urinary problems that affect the normal kidney.
• Many children with kidney dysplasia in only one kidney have no signs or symptoms.

Genetic factors can cause kidney dysplasia. Genes pass information from both parents to the child and determine the child’s traits. Sometimes, parents may pass a gene that has changed, or mutated, causing kidney dysplasia.

Genetic syndromes that affect multiple body systems can also cause kidney dysplasia. A syndrome is a group of symptoms or conditions that may seem unrelated yet are thought to have the same genetic cause. A baby with kidney dysplasia due to a genetic syndrome might also have problems of the

• digestive tract,
• nervous system,
• heart and blood vessels,
• muscles and skeleton, or
• other parts of the urinary tract.

A baby may also develop kidney dysplasia if his or her mother takes certain prescription medications during pregnancy, such as some used to treat seizures and high blood pressure. A mother’s use of illegal drugs, such as cocaine, during pregnancy may also cause kidney dysplasia in her unborn child.

The complications of kidney dysplasia can include

• hydronephrosis of the working kidney. A baby with kidney dysplasia in only one kidney might have other urinary tract defects. When other defects in the urinary tract block the flow of urine, the urine backs up and causes the kidneys and ureters to swell, a condition called hydronephrosis. If left untreated, hydronephrosis can damage the working kidney and reduce its ability to filter blood. Kidney damage may lead to chronic kidney disease (CKD) and kidney failure.
• a urinary tract infection (UTI). A urine blockage may increase a baby’s chance of developing a UTI. Recurring UTIs can also lead to kidney damage.
• high blood pressure.
• a slightly increased chance of developing kidney cancer.
   

If the condition is limited to one kidney and the baby has no signs of kidney dysplasia, no treatment may be necessary. However, the baby should have regular checkups that include

• checking blood pressure.
• testing blood to measure kidney function.
• testing urine for albumin, a protein most often found in blood. Albumin in the urine may be a sign of kidney damage.
• performing periodic ultrasounds to monitor the damaged kidney and to make sure the functioning kidney continues to grow and remains healthy.
   

If the condition is limited to one kidney and the child has no symptoms, no treatment may be necessary. Regular checkups should include blood pressure measurements, blood tests to measure kidney function, and urine testing for protein. Usually the child is monitored with periodic ultrasounds to look at the affected kidney and to make sure the other kidney continues to grow normally and doesn't develop any other problems. Children with urinary tract infections may need to take antibiotics.

Removal of the kidney should be considered only if the kidney

• causes pain
• causes high blood pressure
• shows abnormal changes on ultrasound

Eating, Diet, and Nutrition

Researchers have not found that eating, diet, and nutrition play a role in causing or preventing kidney dysplasia.

Questions to ask your doctor about kidney dysplasia

• Does my child have any other problems in the urinary tract?
• Does my child need to take antibiotics to prevent urinary tract infections?
• Will my child need special medical care?
• How often should my child be checked for high blood pressure and kidney damage?
• How often should the dysplastic kidney and the normal kidney be evaluated by ultrasound?

The long-term outlook for a child with kidney dysplasia in only one kidney is generally good. A person with one working kidney, a condition called solitary kidney, can grow normally and may have few, if any, health problems.

The affected kidney may shrink as the child grows. By age 10,3 the affected kidney may no longer be visible on x-ray or ultrasound. Children and adults with only one working kidney should have regular checkups to test for high blood pressure and kidney damage. A child with urinary tract problems that lead to failure of the working kidney may eventually need dialysis or a kidney transplant.

The long-term outlook for a child with kidney dysplasia in both kidneys is different from the long-term outlook for a child with one dysplastic kidney. A child with kidney dysplasia in both kidneys

• is more likely to develop CKD.
• needs close follow-up with a pediatric nephrologist—a doctor who specializes in caring for children with kidney disease. Children who live in areas that don’t have a pediatric nephrologist available can see a nephrologist who cares for both children and adults.
• may eventually need dialysis or a kidney transplant.

• Researchers have not found a way to prevent kidney dysplasia caused by genetic factors or certain genetic syndromes.
• Pregnant women can prevent kidney dysplasia by avoiding the use of certain prescription medications or illegal drugs during pregnancy.
• Pregnant women should talk with their health care provider before taking any medications during pregnancy.