Horseshoe Kidney : Causes, Signs, Symptoms, Treatment, Complications

Horseshoe kidney is a condition in which the kidneys fuse together. It is a congenital condition that occurs before birth while the fetus is growing and is also known as renal fusion. Kidneys develop individually in the fetus’s lower belly. They slowly move upwards and come to the final position in the back of the body on either side of the spine. Horseshoe kidney occurs when the two kidneys fuse with each other while rising up from the lower belly.

It is observed that 9-10% of kidneys fuse at the bottom forming a U shape.⁽¹⁾

It is still not clear, why this condition occurs in some babies. Exposure to certain drugs and alcohol in the uterus is thought to play a role.⁽¹⁾ It is also known to be common in some people with a specific chromosomal disorder.

There are certain factors that seem to raise the risk of horseshoe kidney.

• People with certain chromosomal disorders including Edward syndrome, Turner syndrome and Down syndrome have a higher chance of suffering from horseshoe kidney disease.⁽²⁾
• Alcohol consumption during pregnancy increases the risk for horseshoe kidney in the fetus.⁽¹⁾
• Glycemia control due to diabetes is another reason.
• Exposure to certain drugs such as thalidomide during pregnancy is also a risk factor for horseshoe kidney disease.⁽¹⁾

7 in 10 people with horseshoe kidney develop symptoms.⁽³⁾ The symptoms of horseshoe kidney may include abdominal pain and nausea.

These people may also suffer from frequent urinary tract infections, which may include the following signs:

• Frequent urination
• Painful urination
• High and low body temperature
• Cloudy and dark urination
• Strong odor in urine
• Pain in the abdomen and back

Kidney stones may also indicate horseshoe kidney and may lead to the following symptoms:

• Excessive pain in one side of the abdomen and groin
• Blood in urine
• Sweating
• Nausea and vomiting

Horseshoe kidney is not a dangerous condition and does not affect how the kidneys work. However, there is an increase in the risk of certain conditions.

Fused kidneys are more positioned towards the front of the body, increasing the risk of injury to the kidney if the person gets hurt.

Also, the position of the blood vessels may differ from the unfused kidneys. Therefore, the treatment of kidney injury in such people may be more difficult.⁽⁴⁾

To avoid the risk of injury, a person may be recommended the following:

• Wearing a medical alert bracelet
• Avoiding contact sports
• Getting regular check-ups
• Keeping medical professionals, teachers, and relatives aware of the conditions

Horseshoe kidney may be detected while undergoing a scan (MRI scan or CT scan) for any other condition.

If a person has symptoms indicating renal fusion, the doctor may look for other signs of kidney problems. The test to determine horseshoe kidney include:

• MRI scan
• CT scan
• Ultrasound scan
• Intravenous pyelogram
• Voiding cystourethrogram, a type of x-ray involving filling the bladder with colored dye
• Radionuclide scan, which involves taking images using a small amount of radioactive chemical known as a tracer
• Kidney function test

There is no cure for horseshoe kidney. Treatment may be needed for symptoms of complications of the condition. If there are no symptoms, no medical intervention may be needed.

The treatment of symptoms may include:

• Antibiotics for urinary tract infection
• Pain management
• Surgery to remove the kidney stones

People with horseshoe kidney can live a full and active life. The location of the kidney, which is in the lower pelvis may interfere with the normal functions of the neighboring structures.

Horseshoe kidney might raise the risk of occurrence of a few complications including:

• Hydronephrosis: This condition involves swelling of the kidney due to the collection of urine.
• Vesicoureteral Reflux: In this condition, the urine flows backward from the bladder into the kidneys.
• Ureteropelvic Junction Obstruction: This condition leads to blockage in the kidney and urine drainage.
• Renal Hypertension: In this condition, there is a narrowing of the arteries carrying blood to the kidneys.
• Polycystic Kidney Disease: It is a condition in which there are benign, noncancerous cysts in the kidney.
• Kidney Cancer: It is more likely to occur in people with kidney fusion. However, it is estimated, that it occurs in 5.2 out of 100,000 people with horseshoe kidney.⁽¹⁾

Horseshoe kidney is a congenital condition. People with this condition are not even aware they have it until it is detected in an imaging study for some other condition. It has no treatment but the symptoms of complications can be managed with supportive care.