Horseshoe kidney (renal fusion) is when a person is born with the kidneys fused together. Seven in ten people with this condition experience symptoms, which can include abdominal pain and nausea. It can also lead to complications, which may need treatment.

Researchers are not certain why some babies develop horseshoe kidney. Exposure to certain drugs or alcohol in the uterus may play a role. It is also more common in people with specific chromosomal disorders.

Some people are unaware that they have horseshoe kidney and do not have symptoms. Others may develop symptoms or complications, which can range from mild to serious.

Read on for more information about horseshoe kidney, including the symptoms, treatment, risks, and impact on quality of life.

A pregnant woman undergoing an ultrasound scan to look for signs of horseshoe kidney. She is lying on a bed wearing a mask.Share on Pinterest
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Horseshoe kidney is a condition that develops when a fetus is still growing inside the uterus.

Usually, two individual kidneys form in the fetus’s lower belly. They slowly move up to take their final position at the back of the body on either side of the spine, just below the ribs.

Horseshoe kidney, or renal fusion, occurs when two individual kidneys fuse together as they rise from the lower belly. In 9 out of 10 cases, the kidneys fuse at the bottom, forming a “U” shape.

Renal fusion is the most common type of fused kidney problem, but it is still relatively rare, occurring in roughly 1 in every 500 people.

Horseshoe kidney, in itself, is typically not dangerous. It does not usually affect how the kidneys work. However, it does raise the risk of certain complications.

Fused kidneys tend to be positioned more toward the front of the body than unfused kidneys, which makes the chances of a kidney injury more likely if a person gets hurt.

The positions of blood vessels can also differ from unfused kidneys. This means horeshoe kidney is more difficult to treat if the person has an accident.

To mitigate these risks, a doctor may recommend:

  • wearing a medical alert bracelet
  • avoiding contact sports
  • having regular checkups
  • making medical professionals, teachers, and relatives aware of the condition

Doctors are not sure what causes horseshoe kidney, but certain factors seem to raise the risk.

People with certain chromosomal disorders have a higher chance of also having horseshoe kidney. These disorders include:

However, having horseshoe kidney does not necessarily mean a person has a chromosomal abnormality. Other factors that scientists associate with horseshoe kidney include:

  • alcohol consumption during pregnancy
  • glycemic control due to diabetes
  • exposure to certain drugs during pregnancy, such as thalidomide

Doctors no longer give thalidomide to pregnant people, but some people affected by the drug still survive today.

As many as 7 in 10 people with renal fusion will develop symptoms. This may include abdominal pain and nausea.

People may also get frequent urinary tract infections (UTIs), which cause:

  • painful urination
  • frequent or urgent urination
  • urine that is cloudy, dark, or pink or has a strong odor
  • a high or low body temperature
  • abdominal or back pain

Kidney stones can also be an indication of horseshoe kidney. This causes:

  • severe pain on one side of the abdomen or groin
  • high temperature
  • sweating
  • nausea or vomiting
  • blood in the urine

Sometimes, people find out they have horseshoe kidney during a scan for another condition. This may include an ultrasound or MRI scan.

However, doctors may also begin looking for signs of kidney problems if a person has symptoms that could indicate renal fusion. Tests doctors can use to determine whether someone has horseshoe kidney include:

  • ultrasound scan
  • MRI scan
  • CT scan
  • intravenous pyelogram, which is an X-ray of the urinary tract
  • voiding cystourethrogram, which is a type of X-ray that involves filling the bladder with a colored dye
  • radionuclide scan, which involves taking images using a small amount of a radioactive chemical known as a “tracer”
  • blood tests to check kidney function

There is no cure for horseshoe kidney. However, people only require treatment if they have symptoms or complications of the condition. If no symptoms are present, a person does not need any medical intervention.

Treatment may include:

  • antibiotics for UTIs
  • surgery to remove kidney stones
  • pain management

Many people with horseshoe kidney lead full, active lives. However, the atypical shape and lower-pelvic location of horseshoe kidney can interfere with the normal functioning of neighboring anatomic structures. As such, the condition does raise the risk of certain complications. These include:

Although kidney cancer is more likely in people with renal fusion, researchers estimate that only 5.2 out of every 100,000 people with horseshoe kidney ever develop this complication.

Doctors may treat these issues using medications or surgery.

Below are answers to some frequently asked questions about horseshoe kidney.

Does horseshoe kidney affect life expectancy?

For most people, horseshoe kidney does not cause serious health problems and thus does not affect their life expectancy.

People with horseshoe kidney are at increased risk of developing other conditions, such as kidney cancer, but this is still uncommon among this group.

Can people with horseshoe kidney drink alcohol?

In most people, having one or two occasional drinks is not harmful. However, drinking alcohol requires the kidneys to work harder, so regular and excessive alcohol drinking can cause or worsen kidney health problems.

Additionally, some medications for horseshoe kidney may interact with alcohol. People who take medications should always talk with their doctor about possible interactions.

Should people with horseshoe kidney follow a special diet?

Doctors do not recommend a specific diet for people with horseshoe kidney, but as diet affects kidney health in general, it is advisable to follow a balanced diet.

The core elements of a healthy diet include:

  • a variety of vegetables and fruits
  • grains, especially whole grains
  • dairy and fortified, plant-based dairy alternatives
  • protein, such as lean meat, poultry, eggs, seafood, beans, peas, lentils, nuts, seeds, and soy
  • healthy fats, such as those from oily fish and nuts

Limit added sugars, saturated fat, sodium, and alcohol.

Horseshoe kidney is a condition that develops during fetal development in the uterus. It causes the kidneys to fuse together, forming one horseshoe-shaped organ.

Researchers do not know the exact cause of horseshoe kidney, but the condition has links with certain genetic conditions and environmental factors.

Some people do not know they have horseshoe kidney, as they do not get symptoms. Others with the condition can develop symptoms or complications, such as UTIs or abdominal pain. Supportive care can help manage this.