Renal Agenesis

What is renal agenesis?

Renal agenesis occurs when a baby is born with only one kidney or no kidneys. Most people have two kidneys, and you need at least one to live. This condition is congenital, which means it’s present at birth.

What is the meaning of “renal agenesis”?

You may better understand this condition when you break down the meaning of its words:

• Renal is the medical term for kidneys.
• Agenesis is the medical term for an organ that fails to fully form as part of fetal development in the uterus (in utero).

What are the types of renal agenesis?

A person may have:

• Unilateral renal agenesis: “Uni-” means one. A child with unilateral renal agenesis is missing a kidney on one side but can live a full life. The one kidney often grows larger than usual as it works harder to compensate for the missing kidney.
• Bilateral renal agenesis: “Bi-” means two. A child is missing both kidneys and ureters (the small tubes that carry urine from the kidneys to the bladder). The lungs are also small and underdeveloped (pulmonary hypoplasia). These combined conditions, known as Potter syndrome, are usually fatal.

What do the kidneys do?

Most people have two kidneys, which are part of the urinary system. Your kidneys help remove wastes from blood, which leave your body when you pee.

How common is renal agenesis?

An estimated 1 in 2,000 babies has unilateral renal agenesis. Bilateral renal agenesis is less common, affecting about 1 in 8,500 newborns. For unknown reasons, the bilateral type is more common in males.

What causes renal agenesis?

A gene change or mutation causes many cases of renal agenesis. Researchers have identified at least seven different linked gene mutations. The gene mutation interferes with the fetal formation of the kidneys during the first trimester of pregnancy.

Less common causes include:

• Gestational diabetes.
• Multiple pregnancy (having twins, triplets or more).
• Use of certain drugs during pregnancy.

Who is at risk for unilateral renal agenesis?

Unilateral renal agenesis is an autosomal dominant disease. This means a child will develop the disease if they inherit a copy of the changed gene from one parent. Often, the parent also has the condition. A parent who has the gene mutation has a 50% chance of passing it to each of their children.

Who is at risk for bilateral renal agenesis?

Bilateral renal agenesis is sometimes inherited as an autosomal recessive disease. This means a child must inherit the same altered gene from each parent in order to develop the disease. The parents are carriers of the mutated gene, but they don’t actually have the disease.

When both parents have the mutated gene, each of their children has a:

• 1 in 4 chance of not getting the mutated gene (no risk of disease).
• 1 in 4 chance of developing renal agenesis.
• 1 in 2 chance of being a carrier who doesn’t develop renal agenesis.

What are the symptoms of renal agenesis?

A child with no working kidneys and underdeveloped lungs (Potter syndrome) will have life-threatening respiratory problems soon after birth.

A child with one working kidney may not have symptoms. When symptoms occur, they include:

• High blood pressure in children.
• High protein levels in urine (proteinuria).
• Vesicoureteral reflux (backflow of urine into the ureters).

Some children with unilateral renal agenesis also have:

• Clubfoot.
• Congenital heart conditions like atrial septal defects (ASD) or ventricular septal defects (VSD).
• Congenital urological anomalies (birth defects that affect the genitals or urinary tract).
• Imperforate anus or anal atresia (a missing anus at the end of the digestive tract).

How is renal agenesis diagnosed during pregnancy?

A prenatal ultrasound during pregnancy often detects low levels of amniotic fluid (oligohydramnios) that can indicate renal agenesis. This ultrasound can also identify missing kidneys. Low urine output from the fetus affects amniotic fluid levels. Without sufficient fluid, a fetus’s lungs can’t grow and develop properly.

How is renal agenesis diagnosed after childbirth?

Imaging scans may take place soon after birth to confirm the diagnosis. In some instances, healthcare providers don’t detect the condition until a child is older. The child may have symptoms that require imaging scans. Or a child may get an ultrasound for an unrelated problem like a urinary tract infection (UTI) that leads to an incidental diagnosis of renal agenesis.

Imaging tests for renal agenesis include:

• Abdominal ultrasound or kidney ultrasound.
• CT scan.
• MRI.

What are the complications of bilateral renal agenesis?

About 4 in 10 fetuses with bilateral renal agenesis die in the uterus before childbirth (a stillbirth). Or they arrive early (a premature birth) before the 37th week of pregnancy. Without kidneys to make urine and amniotic fluid, a fetus's lungs don’t develop properly. Most newborns die from respiratory failure a few hours after childbirth.

How is bilateral renal agenesis treated?

Until recently, a newborn with no kidneys and underdeveloped lungs had little hope of surviving outside of the uterus for more than a few hours. But new experimental treatments offer a reason to have hope. The treatment involves injecting saline (saltwater) solution into the uterus during pregnancy to restore amniotic fluid levels. The fluid allows the fetus’s lungs to develop. After birth, the baby receives dialysis until a kidney transplant procedure can take place. This treatment is still experimental and not widely available.

What are the complications of unilateral renal agenesis?

Unilateral renal agenesis may lead to a premature birth. Your baby may be small and require specialized care in a hospital neonatal intensive care unit (NICU).

Up to half of children born with one kidney develop kidney disease or other problems by the time they’re 30. These problems include:

• High blood pressure.
• Proteinuria.
• Chronic kidney disease and end-stage kidney disease that may require dialysis or a kidney transplant.

How is unilateral renal agenesis treated?

People with unilateral renal agenesis may need medications to lower blood pressure. You or your child should see a nephrologist (a kidney specialist) for annual or more frequent physical examinations, urinalysis and imaging. Your child may also get these tests:

• Kidney function tests.
• Urine protein test.

What steps can you take to protect your one kidney?

Most people with one kidney should follow a kidney-friendly (DASH) diet. This diet reduces sodium and sugar, and increases fiber and potassium.

For children and adults with renal agenesis, these steps can protect kidney health:

• Don’t take nonsteroidal anti-inflammatory drugs (NSAIDs) and certain pain relievers. These can damage the kidneys. Take acetaminophen instead.
• Maintain a healthy weight and stay physically active. However, you should probably avoid high-contact sports like football, soccer and martial arts that increase risk of trauma to the only kidney.
• Regularly check blood pressure at home.

Can you prevent renal agenesis?

If you have a gene mutation linked to renal agenesis, a genetic counselor can discuss ways to lower the risk of passing it to your children. You may have the option to use preimplantation genetic diagnosis (PGD) to identify embryos that don’t have the altered gene. Your provider uses in vitro fertilization (IVF) to implant these embryos into the female reproductive system.

What is the outlook for someone with renal agenesis?

Most people with one kidney lead full, active lives. But some develop kidney problems. It’s important to get regular exams. In the past, infants with no kidneys couldn’t survive. Today, there are experimental therapies that may help a child survive until they’re able to get a kidney transplant.

When should I call the doctor?

Call your healthcare provider if you or your child experience signs of kidney disease, such as:

• Confusion (delirium) or memory problems.
• Decreased urine output.
• Edema (fluid retention) in the legs, feet or ankles.
• Extreme fatigue.
• Headaches.
• Itchy skin (pruritus).
• Loss of appetite.
• Muscle cramps.
• Nausea and vomiting.

What questions should I ask my provider?

You may want to ask your healthcare provider:

• What caused the renal agenesis?
• What treatments do I or my child need?
• Should I make lifestyle or dietary changes?
• Should I look for signs of complications?
• If I get pregnant again, what are the chances my next child will also have renal agenesis?

What’s the difference between renal agenesis and kidney dysplasia?

A child with unilateral renal agenesis only has one kidney. With kidney dysplasia, there are two kidneys but one or both of them are small and/or don’t work well.

A note from Cleveland Clinic

Thousands of people lead productive lives with only one kidney. Still, it can be upsetting to learn that you, your fetus or your older child has renal agenesis. Children born with one kidney (unilateral renal agenesis) are at risk for kidney problems during adulthood. Talk to your child’s healthcare provider about the best ways to protect their kidney health. Bilateral renal agenesis (having no kidneys) is a more serious condition that’s often fatal.