Horseshoe Kidney (Renal Fusion)

What is a horseshoe kidney?

Horseshoe kidney, also called renal fusion, is when two kidneys are fused or joined together. They form a shape like a horseshoe. A horseshoe kidney is also in a different location compared to two typical kidneys. It’s located lower in the pelvis and closer to the front of your body.

Horseshoe kidney occurs as a baby develops before birth. In all babies, kidneys first form in the lower belly. Then kidneys typically move up from the pelvic area and toward the back.

With horseshoe kidney, instead of moving into the usual position on either side of the spine, kidneys become attached at their lower end. When they fuse, they form a U shape.

What do the kidneys do?

The kidneys are part of your urinary system. Kidneys filter your blood to absorb and regulate the electrolytes your body needs. They also clean your blood by removing extra water and waste. The waste travels from the kidneys to the bladder and leaves the body through the urethra as urine.

How does horseshoe kidney affect me?

Many people with horseshoe kidney do not have symptoms. But horseshoe kidney can make you more prone to problems such as urinary tract infections (UTIs) and issues with how urine flows and leaves your body.

How common is horseshoe kidney?

Horseshoe kidney affects about 1 in 500 people. It affects more men than women.

What other conditions are associated with horseshoe kidney?

Horseshoe kidney often affects people born with certain syndromes, including:

Chromosomal conditions:

• Down syndrome.
• Turner syndrome.
• Trisomy 13 (Patau syndrome) and trisomy 18 (Edwards syndrome), serious conditions that cause severe birth defects (congenital disabilities).

Nonchromosomal conditions:

• Ellis-van Creveld syndrome.
• Fanconi anemia.
• Goltz syndrome.
• Kabuki syndrome.
• Pallister-Hall syndrome.
• VACTERL association.

What causes horseshoe kidney?

Researchers don’t know what causes horseshoe kidney. It’s related to a problem with how the genes instruct your kidneys to form. This problem happens before a baby is born.

Environmental factors may play a role as well. Some babies with renal fusion had exposure to certain toxins before birth, such as drugs or alcohol.

What are the symptoms of horseshoe kidney?

Around 7 in 10 people with renal fusion have symptoms of kidney problems. Many of these symptoms are signs of complications related to horseshoe kidney.

Common symptoms include:

• Abdominal (belly) pain.
• Nausea.
• Frequent urinary tract infections (UTIs), which may cause pain when you pee, along with fever.
• Kidney stones, which can cause abdominal pain, blood in the urine (hematuria) and pain when you pee.

What are the complications of horseshoe kidney?

People with horseshoe kidney are more prone to developing:

• Vesicoureteral reflux (VUR), when urine flows backward from your bladder back toward your kidneys
• Ureteropelvic junction (UPJ) obstruction, when part of your kidney and urine drainage is blocked.
• Hydronephrosis, a collection of urine in the center of the kidneys, makes the kidneys swell.
• Polycystic kidney disease, when noncancerous cysts (small growths) form in the kidneys.
• Renovascular hypertension or renal artery stenosis, high blood pressure that happens when the arteries that carry blood to your kidneys narrow.
• Wilms tumor, a type of kidney tumor that happens in children.

While kidney cancer is rare, people with horseshoe kidney are more likely than people with typical kidneys to develop cancerous tumors.

Look for signs of kidney tumors, which can include:

• Blood in the urine (hematuria).
• A mass (bulge or lump) in the abdomen.
• Flank pain (in your sides).

How is horseshoe kidney diagnosed?

Many times, healthcare providers notice horseshoe kidney while diagnosing or treating another condition.

If you see your healthcare provider because of kidney-related symptoms, your provider will do a physical exam. You may also have urinalysis to check for blood or other elements in your urine.

Kidney function tests can see how well your kidneys are working. These may include:

• Estimated glomerular filtration rate (eGFR), a blood test to check how much blood your kidneys filter every minute.
• Blood urea nitrogen (BUN) test.
• Creatinine test.

You may also need imaging tests, including:

• Renal (kidney) ultrasound.
• Intravenous pyelogram, an X-ray of your kidneys, ureters and bladder.
• Voiding cystourethrogram (VCUG).
• Radionuclide scan, an imaging technique that uses a small dose of a radioactive substance to detect any problems.
• Imaging tests such as an MRI or CT scan.

How is horseshoe kidney treated?

There’s no cure for horseshoe kidney. If you’re not having symptoms, you may not need any treatment.

If you’re having symptoms, your provider can offer treatments to improve symptoms. For example, antibiotics can treat a bacterial infection.

Surgery can:

• Restore urine flow.
• Correct vesicoureteral reflux.
• Remove kidney stones.

How can I prevent horseshoe kidney?

There is no known way to prevent horseshoe kidney.

What’s the outlook for people with horseshoe kidney?

Horseshoe kidney usually does not cause serious health problems. You or your child may need ongoing care to manage symptoms, but you can live a full, active life with horseshoe kidney. Horseshoe kidney usually does not affect life expectancy.

People with horseshoe kidney may be at higher risk for kidney (renal) cancer. Keep an eye out for symptoms, and talk to your healthcare provider about steps you should take to stay on top of your kidney health.

When should I see a healthcare provider for horseshoe kidney?

See your healthcare provider if you notice these symptoms in you or your child:

• Blood in the urine.
• Frequent UTIs.
• Pain, mass or swelling in the abdomen.

How can I take care of myself if I have horseshoe kidney?

A horseshoe kidney is closer to the front of the body than a typical kidney. There’s a higher chance it can be damaged in an accident, while playing sports or due to another physical injury. You may want to:

• Wear a medical alert bracelet: A medical alert bracelet lets emergency responders know to be aware of possible kidney damage in the event of an accident or other trauma.
• Avoid contact sports: This is especially important for children with horseshoe kidney. Contact sports, such as tackle football, could injure the kidney.

Because this condition is so rare, your care team should work together to help educate you, your child and your family about how to live safely with horseshoe kidney. Your care team should include:

• Pediatrician.
• Nephrologist (kidney specialist).
• Urologist (urinary tract specialist).
• Other specialists as necessary.

What else should I ask my healthcare provider?

If you or your child has horseshoe kidney, ask your healthcare provider:

• What treatment do you recommend?
• Should I get a medical alert bracelet?
• Will I need surgery?
• Should I get screened for kidney cancer?
• Do I need other preventive tests?
• How else can I keep my kidney healthy?

A note from Cleveland Clinic

A horseshoe kidney, also called renal fusion, is a condition a child is born with. The two kidneys fuse before birth. Many people don’t experience symptoms, but complications from horseshoe kidney can occur. Most often, people have frequent UTIs and kidney stones. There’s no cure for horseshoe kidney, but you can stay healthy by treating any related conditions that might arise. Take extra precautions to avoid damage or injury to the kidney. If you or your child has frequent UTIs, urinary changes or abdominal pain, talk to your healthcare provider.