Characteristics of the Nutcracker Syndrome

Science doesn't fully understand the causes of nutcracker syndrome, a rare disease that affects the kidney. The good news is it's treatable. Learn more in this article!
Characteristics of the Nutcracker Syndrome

Last update: 27 May, 2021

Renal nutcracker syndrome is a rare disease. It happens when the left renal vein is squeezed by other structures like a walnut inside a nutcracker (hence the name).

The compression of this vein induces narrowing of the renal vein. For this reason, its pressure increases considerably. It all leads to the appearance of small abnormal ducts called fistulas, with the consequent renal bleeding. This syndrome, also known as nutcracker syndrome, was first described in 1950.

The disorders caused by this syndrome occur when the left renal vein, responsible for transporting purified blood through the left kidney, is compressed. The condition can occur in children, teenagers, and adults. Furthermore, it could be mild or severe depending on its intensity and there’s a treatment for all cases.

Symptomatology of the nutcracker syndrome

Some people are asymptomatic but others do experience the signs of this condition. There’s also a group of patients who present severe and persistent symptoms in the genitourinary area.

One of the most common symptoms is hematuria, the presence of blood in the urine. It either has a reddish coloration or a few drops of blood. Other signs could be the appearance of varicose veins in the legs, pelvic congestion, or low back pain on one side only.

In the case of women, there may be a decrease or dysregulation of the menstrual cycle. Both men and women may experience pain during sex — dyspareunia. Another symptom is the loss of protein when passing urine, scientifically called orthostatic proteinuria.

This disease is fairly benign but some of its symptoms may lead to anemia, as in cases where there’s loss of blood through the urine.

Blood in the urine.
Hematuria is the presence of blood in the urine and can be a sign of renal nutcracker syndrome.

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Types of nutcracker syndrome

There are three:

  • The most common is the anterior type and occurs when the aorta or the abdominal and mesenteric arteries compress the left renal vein
  • The posterior type is when an artery, usually the abdominal, and the vertebrae of the spine trap the left renal vein
  • The third type is the combined type, which is also the rarest and happens when the two anterior arteries pinch the left renal vein while the aorta and the spine compress the posterior part

Origin of the disease

The origin of renal nutcracker syndrome is unclear. However, the scientific community already ruled out genetic or hereditary causes. There’s evidence of it occurring frequently among the Eastern population though.

However, professionals from the urology service of the Hospital General Universitario Gregorio Marañón, of the Universidad Complutense de Madrid, said the disease could originate in the embryo. Moreover, it could be due to an anomaly in the separation between the aorta and the superior mesenteric artery.

In the case of infants with renal nutcracker syndrome, it could be due to abrupt changes in their body — this is typical of growth. In these cases, the changes don’t occur proportionately but cause the anomaly.

An illustration of the kidneys.
The origin of the disease isn’t clear and there are several hypotheses about it.

What causes this condition in adults?

In adults, this impingement may be due to different causes. Some of them may be:

  • Pancreatic tumors
  • Swelling of the para-aortic lymph nodes, which are the ones in front of the base of the spine
  • Tumors behind the stomach or intestines
  • Abdominal aortic aneurysm
  • Duplication of the left renal vein or abnormal fall of the kidney into the pelvis when a person stands up

There are conditions associated with the syndrome, such as hyperlordosis – an evident protrusion of the curve of the spine inwards – and low body mass index. In addition, there seems to be a direct relationship between a person’s low weight and the appearance of renal nutcracker syndrome. This is because the presence of fat in the area facilitates more space between the vein and the kidney.

Nutcracker syndrome in nephrology

A nephrologist is a specialist who deals with the treatment and follow-up of renal nutcracker syndrome. In their absence, urologists are also qualified to deal with it. Don’t hesitate to consult one of these professionals to clear any doubts you might have if you notice any alterations in your urine.

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