Struvite Stones

What are struvite stones?

Struvite stones are caused by infections in the upper urinary tract. A kidney stone is a hard object that is made from chemicals in the urine. After formation, the stone may stay in the kidney or travel down the urinary tract into the ureter. Stones that don't move may cause significant pain, urinary outflow obstruction, infection, or other health problems.

What are the symptoms of struvite stones?

A stone that is small enough can pass through with no symptoms. However, a stone that is too large to pass through may cause significant pain, back-up of urine, and other health problems. Speak with a healthcare professional if you feel any of these symptoms:

  • Severe pain on either side of your lower back
  • Nausea or vomiting
  • Fever and chills
  • Frequent need to urinate
  • Pain when you urinate
  • Blood in the urine
  • Urine that smells bad or looks cloudy

Symptoms related to a UTI include a persistent urge to urinate, a burning sensation during urination, or passing frequent and small amounts of urine. Urine that looks red, pink or dark means there is blood in the urine.

What causes struvite stones?

Struvite stones are caused by an upper urinary tract infection (UTI) from bacteria. Ammonia produced as a waste product by the bacteria can make the urine less acidic (or more alkaline). Struvite stones form when the urine becomes more alkaline. The main chemicals in a struvite stone include struvite (magnesium ammonium phosphate) and calcium carbon-apatite. These stones can grow quickly and become quite large. This can happen with few symptoms at first or little warning.

How can struvite stones be prevented?

To prevent future struvite stones, your doctor may prescribe certain medicines. Acetohydroxamic acid (AHA) is used to stop the bacteria from making ammonia, which can cause struvite stones to grow. You might also be given antibiotics for a while after a stone is removed. This may help prevent future UTIs, which can lead to stones.

Drinking enough water each day is important in maintaining overall health and will help keep your urine less concentrated with waste products. Darker urine is more concentrated, so your urine should appear light yellow to clear if you are well hydrated. Drinking enough fluids to make at least two liters of urine per day may be recommended. Fluid restrictions might apply if you have advanced kidney disease, so speak with a healthcare professional about the right amount of water for that’s best you.

How is a struvite stone diagnosed?

Diagnosis of a kidney stone starts with a medical history, physical examination, imaging tests, urine and blood testing, and stone analysis. Blood and urine can be tested for abnormal levels of certain chemicals. You may be asked to collect your urine for 24 hours to test for uric acid or other chemicals. The urine may be examined for magnesium ammonium phosphate crystals in the urine sediment.

Imaging tests can be used to locate stones in the body. Ultrasound uses a device to bounce safe, painless sound waves off organs and create an image of their structure. Many healthcare professionals feel that this is the best screening test to find stones. Computerized tomography (CT) scans uses a beam of X-rays and computers to create images and look for stones inside the kidneys.

A stone that comes out of the body and saved can be analyzed in order to find the type of stone and its cause. Knowing the type of stone can also help with a plan for prevention.

What is the treatment for struvite stones?

For many people with kidney stones, drinking more water may be the first recommendation. Medications can also be used either for pain or to help the stone pass. Medications can include thiazide diuretics (water pills) or tamsulosin (to relax the ureter and help the stone pass). Antibiotics are used to stop a bacterial infection causing a UTI.

However, in the case with struvite stones, passage of the stone is rare. In many cases, the stone is too large to pass through, and surgical procedures are needed to break down larger stones or remove them. A ureteroscopy uses a small scope to remove the stone. Shock wave lithotripsy (SWL) uses high-energy acoustic pulses to break up the stone into smaller pieces for passing. Percutaneous nephrolithotomy (PCNL) removes the stone surgically through the back. In the case with struvite stones, surgical management requires complete stone removal, usually with a procedure such as PCNL.