What are struvite stones?

Struvite stones are a type of hard mineral deposit that can form in your kidneys. Stones form when minerals like calcium and phosphate crystallize inside your kidneys and stick together. Struvite is a mineral that’s produced by bacteria in your urinary tract.

About 10 to 15 percent of all kidney stones are made from struvite. This type of stone is more common in women than in men.

Struvite stones can grow very quickly. Eventually, they can block your kidney, ureter, or bladder and damage your kidney.

Symptoms of struvite stones are similar to those of other types of stones, and can include:

Bacteria in your urinary tract produce struvite when they break down the waste product urea into ammonia. For struvite to be produced, your urine needs to be alkaline. Having a urinary tract infection can make your urine alkaline. Struvite stones often form in women who have a urinary tract infection.

Your doctor will do one or more of the following tests to help diagnose the cause of your symptoms, and find out if you have struvite stones:

  • Blood tests. Your doctor might collect a blood sample to check levels of waste products like calcium and uric acid that can form into stones.
  • Urine testing. A urinalysis checks a sample of your urine to diagnose a urinary tract infection. The doctor might perform a culture on that sample to see if your urine contains bacteria.
  • 24-hour urine culture. For this test, you collect all of your urine in a 24-hour period. Then a laboratory checks the culture for stone-forming substances like calcium, oxalate, and uric acid.
  • X-ray. Radiation creates a picture of your kidneys and other organs in your urinary tract.
  • CT scan. This test takes X-ray images from many different angles to produce detailed pictures of your urinary tract.
  • MRI scan. A powerful magnetic field and radio waves make detailed pictures of your urinary tract.
  • Intravenous urography. This test uses X-rays and a special dye to look for problems with your kidneys, ureters, and bladder.

It’s important to treat struvite stones because if they grow large enough, they can damage your kidney and lead to life-threatening infections. Doctors treat these stones with shock wave lithotripsy (SWL) or percutaneous nephrolithotomy (PNL).

PNL is the preferred treatment for people with stones that are too large to be broken up by SWL. The surgeon makes a small incision in your back and inserts a scope and several small instruments. Then the stone is removed through the incision. You’ll be asleep during the surgery. You may have to stay in the hospital for a couple of days afterward.

SWL uses intense shock waves directed from a machine outside your body to break up the stones into tiny pieces. After this treatment, the pieces of stone will pass through your urinary tract and come out in your urine. If your stones are very large or you have a lot of them, you might need to have this procedure more than once.

If PNL and SWL aren’t options, your doctor might recommend that you have open surgery to remove the stones. The surgeon will make a larger incision in your abdomen or side and remove the stones from your kidney. If your kidney has been very damaged by stones, it may need to be removed.

Diet may not be effective at preventing struvite stones because they’re caused by infections. But certain fluids may make the environment in your urinary tract more inhospitable to stone growth. These include:

As well, try to drink extra fluids. Crystals are less likely to form in dilute (watery) urine. Some doctors recommend drinking enough water and other fluids to produce 2 quarts of urine daily. Ask your doctor how much fluid you should drink.

After surgery, your doctor may prescribe medicine to prevent more stones from forming. Acetohydroxamic acid (AHA) blocks the buildup of ammonia that can cause struvite stones to grow.

If you have a recurring issue with struvite stones, your doctor may recommend taking small doses of antibiotics long term. This may help prevent the urinary tract infections that can lead to stones.

See your doctor if you have kidney stone symptoms like back and side pain, fever, and frequent urination. Your doctor can do tests to find out if you have urinary stones and what type they are.

Treatments like PNL and SWL can remove most struvite stones — especially if the stones are small. If you have large stones, there may be fragments left over after surgery. Some people will need to have a second surgery or other treatments.

Call your doctor right away or get emergency medical help for these more severe symptoms of a kidney stone: