All You Need To Know About The Medullary Sponge Kidney Condition

Medullary sponge kidney (MSK) is a condition present at birth in which small cysts develop in the medulla tubules, resulting in a sponge-like appearance. The cysts, which are tiny fluid-filled sacs, block the urine from flowing freely through these tubules. 

This congenital disorder, while rare, can affect one or both kidneys.

Signs and symptoms of medullary sponge kidney

The medullary sponge kidney is benign and thus has no symptoms. However, it can result in complications such as urinary tract infections (UTIs) and kidney stones. 

The signs and symptoms of MSK include:

• Burning sensation when urinating

• Cramps in the groin or lower abdomen

• Fever

• Chills

• Vomiting

• Foul-smelling urine

• Pain in the back

• Cloudy urine

• Blood in the urine

If you experience the above symptoms of kidney disease, consult your doctor. They will conduct a test to determine whether you have MSK.

Causes of medullary sponge kidney

The exact cause of the medullary sponge kidney is unknown, and most conditions do not seem to be genetic. The condition is more common in women than in men.

Complications resulting from medullary sponge kidney

Medullary sponge kidneys can lead to the formation of kidney stones, UTIs, and hematuria or blood in the urine. 

In rare instances, it can result in more severe conditions, with kidney failure occurring in approximately 10% of people with MSK.

Diagnosis of MSK

A doctor can diagnose MSK by conducting physical exams and imaging studies.

Physical examination

A physical exam cannot point out the existence of a medullary sponge kidney but can alert the doctor about potential problems with your kidney, which can prompt them to conduct further tests. Symptoms such as blood in urine and pain can inform the doctor’s decision to carry out imaging studies.

Imaging studies       

Doctors can use the following techniques to observe the structure and constitution of your body organs, including the kidneys.

• Ultrasound

• Computerized tomography (CT) scan

• Intravenous pyelogram

Ultrasound

This imaging technique uses sound waves to create images of your internal body structure, including your kidneys. An imaging technician uses a transducer to bounce soundwaves off the organs to show kidney stones and calcium deposits in your kidney.

The test is painless and takes 20–30 minutes, with the results available within a day.

The doctor will typically ask you to lie down. They will apply an ultrasound gel that removes the air pockets around your skin, enabling the sound waves to bounce off the tissues and produce clear images when a transducer is placed over your abdomen.

Computerized tomography scan

Popularly known as CT scans, these techniques use x-rays and computer technology to generate images of your kidney. The technician gives you an iodine solution to drink and injects you with contrast material to enhance the clarity of the structure before you begin the imaging.

They may then ask you to lie on a table that slides through the tube where the x-rays are taken. CT scans can show expanded or stretched tubules, which can help diagnose your condition.

Intravenous pyelogram

The healthcare professional injects contrast material into your arm, which then travels through the bloodstream into your kidney before being excreted into the urine. 

The contrast material makes the urine visible on the x-ray, thus enabling the observer to see the blockage in the urinary tract and cysts that show as clusters of light.

Treatment of medullary sponge kidney

Researchers have yet to discover ways to reverse the condition. Still, your doctor can work on dealing with conditions such as UTIs and kidney stones resulting from medullary sponge kidneys.

The doctor prescribes antibiotics if you have a UTI. The type of medication will depend on the type of bacteria causing the infection. Where kidney stones are apparent, the doctor employs the following treatments:

Shock wave lithotripsy

The doctor can use shock wave lithotripsy to dismantle kidney stones into smaller pieces that can pass through the urinary tract. The doctor administers anesthesia while carrying out this procedure.

Cystoscopy and ureteroscopy

Urologists carry out these procedures to have a look at the urinary tract.

In cystoscopy, the doctor uses a cystoscope, a tube-like instrument with an eyepiece, to view the urethra and bladder in search of potential stones. A cystoscope is a long, thin optical instrument with an eyepiece at one end.

The ureteroscope is typically longer and thinner than a cystoscope and is used to view the lining of the ureter and kidneys. If the doctor observes any stones in your system, they may remove them or dismantle them into smaller pieces. Cystoscopy and ureteroscopy are performed with anesthesia. It is a quick procedure; you can usually leave within the day.

Before undergoing either of the procedures, the doctor will likely inquire about your medical history to determine their necessity. You will also need to provide a urine sample to test for urinary tract infections. If you have a UTI, the doctor will likely give you antibiotics.

To provide information such as any potential allergies. The process is brief, only taking 15 to 20 minutes. It is also not painful, and the doctor may use sedatives or general anesthesia to help you sleep while they are carrying out the procedure.

To begin the process, the urologist inserts the cystoscope into the urethra and gradually guides it into the bladder before filling it with saline liquid for a better view of the bladder wall and lining of the urethra. If they determine a problem such as kidney stones, they may insert instruments through the cystoscope to treat or remove it.

The doctor uses the same process for ureteroscopy but focuses on viewing the pelvis lining instead.

Percutaneous nephrolithotomy

When conducting the percutaneous nephrolithotomy procedure, the doctor makes a small incision in your back and inserts the nephroscope to locate and remove the kidney stone. If the stone is sizable, the doctor may use a laser to break it into smaller pieces that can get out of the body through the urine.¹

Prevention of medullary sponge kidney

Experts have yet to discover ways of preventing medullary sponge kidney, but there are medications and dietary adjustments that can help you with the resulting UTIs and kidney stones.

If you have been diagnosed with MSK, the doctor may recommend a low-dose antibiotic to prevent infections from recurring.

Some of the dietary changes you could make include drinking plenty of water and other fluids that can help remove bacteria from the urinary tract and dilute the urine to prevent the formation of kidney stones.

You could also try ingesting less sodium, as this will reduce the risk of you developing kidney stones. Diets with high amounts of sodium can increase the excretion of calcium, which plays a role in the formation of kidney stones.

Avoiding foods rich in oxalates, such as chocolate, spinach, walnuts, parsley, and rhubarb, can help prevent the formation of kidney stones. It is, however, not advisable to avoid foods rich in calcium, such as milk, cheese, and yogurt, since a diet low in calcium increases the risk of kidney stones.

However, high animal protein content in foods such as meat, fish, and eggs also increases the risk of uric acid stones and calcium stones developing in the renal system. Consult your healthcare professional or dietitian on the right foods for your condition.

Your doctor may also recommend the following medications to prevent kidney stones if they determine that you are at significant risk of developing them.

• Thiazide diuretics — These work by reducing the amount of calcium passing into the urine from the bloodstream, thus preventing the growth of calcium stones

• Citrate salts — They prevent the formation of calcium crystals by binding to the calcium in the urine

• Allopurinol — They lower the uric acid levels in urine by inhibiting the breakdown of purines to uric acid and, by doing so, prevent the formation of uric acid stones

• Dietary supplements — Magnesium usually attaches to oxalate in the urine, preventing the formation of calcium oxalate stones

When to see a doctor

You should see a doctor if you experience blood in your urine, pain in your groin, abdomen, or lower back, and fever or chills. 

While the symptoms may not always point to medullary sponge kidneys, the doctor will be able to diagnose to determine what is precisely ailing you and offer the requisite treatment.

The lowdown

The medullary sponge kidney is a congenital disorder characterized by the formation of cysts in tubules of the medulla in the kidney, blocking the passage of urine. The condition does not exhibit symptoms but may lead to urinary tract infections or kidney stones.

Therefore, you should consult your doctor if you experience issues with your renal system. The doctor can make a proper diagnosis and issue the correct treatment.

If diagnosed with the disease, take the medication and adjust your diet to help deal with the condition. Your doctor or dietitian will offer advice on what constitutes a healthy diet.

Frequently asked questions

Is medullary sponge kidney fatal?

No. The condition is benign, has no symptoms, and rarely results in complications beyond kidney stones and urinary tract infections, which can be treated by long-term use of antibiotics and healthy dietary practices. The chances of developing complications such as chronic disease and kidney failure are low.

Who is more likely to develop the disease?

Within the pool of people likely to develop calcium-based kidney stones, women develop medullary sponge kidneys more often. The condition affects people of all races.

How common is the medullary sponge kidney?

The condition is very rare, affecting only 1 in 1,000 to 5,000 people in the US.²

What does a medullary sponge kidney feel like?

Since the condition is benign, you are unlikely to feel anything unusual as the condition may remain unnoticeable until adolescence or adulthood. It is not until you start experiencing symptoms such as painful discomfort when passing urine or changes such as blood in your urine that a doctor may suspect a case of MSK.

Is medullary sponge kidney serious?

The condition is not chronic and does not result in frequent hospitalization or complex medical procedures. The interventions to treat associated complications such as UTIs and kidney stones are safe and unlikely to take much of your time. You will thus lead a normal healthy life and carry on with most of your activities even when diagnosed with the condition.

Does a urinary tract infection or kidney stones mean that you have MSK?

You cannot determine that you have MSK unless your doctor has made that diagnosis. While a UTI  could signal that you have a medullary sponge kidney, it is not a foregone conclusion. 

The UTI could also be the result of the following:

• Sexual activity

• Menopause

• Certain types of birth control

• Diabetes

• Another problem in your urinary tract that blocks the normal passage of urine

Similarly, kidney stones could be the result of other causes, such as:

• Cystic kidney disease

• Hyperparathyroidism

• Hyperoxaluria

• Obesity

• Renal tubular acidosis

However, 12% to 20% of patients diagnosed with calcium-based kidney stones tend to have the condition.

Is medullary sponge kidney a disability?

While MSK is a congenital disorder, it does not impair your ability to perform daily activities or interact with the world around you. You will lead a healthy life as anyone else if you have the condition.

What happens if complications resulting from the medullary sponge kidney remain unaddressed?

You risk developing complications if you do not treat UTIs and kidney stones resulting from medullary sponge kidneys. A UTI left untreated may see the bacteria progress from the bladder to your ureter and kidneys. You also risk developing chronic kidney disease if you do not treat kidney stones that impede urine flow.