Medullary sponge kidney, also called Cacchi-Ricci disease, causes cysts to form in the small tubes inside the kidneys. It is present at birth, but doctors do not know the cause.

The cysts are usually benign, or harmless, but they can cause symptoms such as blood in the urine or frequent urinary tract infections (UTIs).

Many people with the condition do not know they have it and receive a diagnosis in adulthood if it causes symptoms. However, symptoms are usually minor or nonexistent.

Learn more about medullary sponge kidney, its symptoms, diagnosis, treatment options, and more.

A scan depicting medullary sponge kidney.Share on Pinterest
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The kidneys are a complex network of ducts and tubules, which are small tubes.

Medullary sponge kidney causes cysts to form in the ducts or tubules. It usually affects both kidneys.

The cysts can make the ducts swollen and dilated, which can cause kidney stones, UTIs, or blood in the urine in some cases.

It is congenital, which means that it is present at birth.

Doctors do not know what causes it. Although some experts theorize that it may be genetic, there is limited research on the topic.

Medullary sponge kidney usually causes no symptoms. This is why it often goes undiagnosed.

When symptoms do appear, they typically manifest in adulthood, even though the diagnosis is present at birth.

When symptoms do appear, they may include:

Frequent kidney stones may be a sign of medullary sponge kidney. According to a research article, 12–20% of people with recurring calcium kidney stones have the condition.

Among women and people under 20 years old, the figure may be even higher — up to 30%.

A person with medullary sponge kidney may not receive a diagnosis until adulthood.

Sometimes, the condition is an incidental finding when a doctor is looking for something else, such as a kidney stone. In other cases, a doctor may recommend testing based on frequent infections or kidney stones.

To diagnose the condition, a doctor may order one or more imaging tests such as magnetic resonance imaging (MRI) or computed tomography (CT) scan. A CT urogram uses contrast dye injected into a vein to look at the veins in and around the kidneys and can show changes in the kidneys consistent with medullary sponge kidney.

Researchers do not know what causes medullary sponge kidney.

It is usually sporadic, which means that it appears in someone without a family history. Researchers have not identified a specific gene that causes it.

However, some instances do run in families, and a small number of cases may occur due to a genetic variant a person carries.

People with medullary sponge kidney are more likely to have hemihyperplasia, also known as hemihypertrophy, which causes one side of the body to grow larger than the other. There is also a higher prevalence of the condition among people with hemihyperplasia. At present, experts do not fully understand the reason for this association.

There are no specific risk factors for this medullary sponge kidney, and there are no known interventions to prevent it.

Medullary sponge kidney causes nephrocalcinosis, which means that there are calcium salts in the kidneys.

Several other conditions also cause nephrocalcinosis, including:

Additionally, a doctor may misdiagnose a person with medullary sponge kidney due to being so rare. The condition often presents as a UTI or kidney stones, so a doctor may mistake it for those conditions in someone who presents for the first time with a UTI or kidney stones.

Unlike some other kidney diseases, medullary sponge kidney does not usually cause serious symptoms.

Medullary sponge kidney only requires treatment when it causes symptoms.

Doctors may recommend lifestyle changes to prevent the formation of kidney stones. These include:

  • eating a low sodium, high potassium, and low to moderate protein diet
  • drinking enough water to produce 2,000 milliliters of urine daily
  • consuming potassium citrate supplements

If a person has a UTI, they may need antibiotics to treat it.

Additionally, if a person has kidney stones, they may require treatment. If a kidney stone becomes stuck, a doctor may have to surgically remove it. This usually involves lithotripsy, a procedure that removes kidney stones with lasers or shock waves.

Most people with medullary sponge kidneys have few or no symptoms. When symptoms do appear, they include issues such as UTIs and kidney stones, which proper treatment can manage.

There is no cure for medullary sponge kidneys, but the disease does not affect life expectancy or quality of life in most people.

However, an estimated 10% of people with this diagnosis eventually develop kidney failure. Kidney failure is life threatening and requires either a kidney transplant or dialysis.

Additionally, untreated UTIs or kidney stones may cause serious symptoms such as sepsis.

Medullary sponge kidney is not usually harmful, and many people with this condition may not even realize they have it. However, it is a common cause of recurring kidney stones and may also cause UTIs and bloody urine.

A doctor may discover this condition in a person with kidney stones or while checking the kidneys for something else. Treatment focuses on symptom management.