Brief overview
- Causes: Congenital malformation of the renal system
- Course & Prognosis: Usually no limitations and not life-threatening; more rarely complications such as renal tumors.
- Symptoms: Mostly without symptoms, sometimes urinary dysfunction, urinary tract infections; concomitant symptoms due to other diseases such as kidney tumors
- Examinations & Diagnosis: Ultrasound, x-ray examination, magnetic resonance imaging (MRI) or computed tomography (CT), urine and blood tests, excretory urography (AUG)
- Treatment: Without symptoms, no treatment necessary; if necessary, medication for secondary diseases (e.g. antibiotics), surgery if necessary
What is a horseshoe kidney?
The connection between the two kidneys (called the isthmus) consists either of functional kidney tissue or of cord-like connective tissue. Both kidneys function independently of each other, so that the horseshoe kidney also usually functions normally.
The horseshoe kidney is the most common fusion anomaly of the kidneys. About one in 400 children is born with it. Boys are affected more often than girls.
How does a horseshoe kidney develop?
Horseshoe kidney is a congenital developmental disorder that leads to a malformation of the kidneys. Normally, the two kidney systems develop in the unborn child without direct connection to each other in the pelvic region. From there, they then ascend to the lumbar region, turning so that the renal pelvises face inward (medially).
Is a horseshoe kidney dangerous?
Some people with a horseshoe kidney have no complaints and do not develop any secondary diseases. Others, however, suffer more frequently from secondary diseases such as urinary tract infections or develop kidney tumors. In most cases, however, people with a horseshoe kidney lead an undisturbed life without any significant restriction in their quality of life and life expectancy.
Depending on the severity of the malformation and individual risk factors, regular check-ups are indicated. If you have a horseshoe kidney, point this out during the initial consultation when you visit your doctor. This information may be important for clarifying various complaints.
What are signs of a horseshoe kidney?
Therefore, if a person is known to have a horseshoe kidney, special attention should be paid to the following symptoms:
- Decrease in urine volume
- Change in growth rate in children
- Blood or stones in the urine
- Change in urine odor
- Cramping flank pain
- Groin or deep back pain
- Sudden increase in body temperature (fever)
If any of these symptoms occur, a visit to the doctor is strongly advised to determine the exact cause.
Other malformations or genetic diseases
About one third of all people with a horseshoe kidney have additional malformations that also affect the urogenital tract (urinary and sexual apparatus) or other parts of the body (such as the digestive organs).
Certain genetic disorders occur more often in association with horseshoe kidney, namely Ulrich Turner syndrome and trisomy 18 (Edwards syndrome):
In trisomy 18, chromosome 18 is present in triplicate (instead of duplicate). This results in complex malformations – in addition to a horseshoe kidney, for example, malformations in the head area (such as small face, small mouth, large occiput), short stature and a characteristic finger posture.
How is a horseshoe kidney diagnosed?
Since many people with a horseshoe kidney do not show any symptoms, doctors often discover the malformation only by chance – for example, during an ultrasound examination when kidney disease is suspected. The shape and position of the kidney can be easily and quickly examined on ultrasound, and a horseshoe kidney is immediately recognizable on the images.
If more detailed information about the malformation is required, magnetic resonance imaging (MRI) or computed tomography (CT) can be used to produce a detailed cross-sectional image of all organs in the abdominal cavity.
If urine outflow is disturbed or there is urine reflux from the bladder toward the kidney, excretory urography (AUG) can be used to determine the severity and exact location of the disturbance. For this purpose, patients are injected with a contrast medium that the body excretes via the kidneys.
Immediately after administration, the physician takes x-rays at regular intervals, which show the path of the contrast medium through the kidneys and the draining urinary tract and bladder. The contrast medium depicts these structures particularly well. This makes it easy to detect any constrictions or backflow.
What is the therapy for a horseshoe kidney?
If kidney tumors have developed, which occur somewhat more frequently in people with a horseshoe kidney than in people with “normal” kidneys, treatment is usually also required. Such tumors are either benign (such as angiomyolipoma) or malignant (such as renal cell carcinoma, Wilms tumor).
