What causes struvite kidney stones

struvite kidney stonesWhile kidney stones are familiar to most people, struvite kidney stones may not be. Struvite kidney stones have sharp, uneven edges and they tend to grow quickly, leading to a malfunction of the kidney. This type of stone requires immediate medical attention.

The kidney plays an important role in the human body. It filters waste, balances fluid volume, balances electrolytes, and helps maintain blood pressure. Kidney stones are a common disorder of the urinary tract. Struvite kidney stones are a mix of magnesium, ammonium, and phosphate. They are found more in women than in men because women tend to develop urinary tract infections more often. Since struvite stones grow so fast, they have a strong potential to cause impairment to the kidney. Thankfully, advances in medicine mean that management and treatment of kidney stones have improved significantly.

Prevalence of struvite kidney stones


Kidney stones made up of calcium oxalate are rather common in the Western world and struvite kidney stones make up about 30 percent of urinary tract stones. In the U.S., it is estimated that anywhere between 10 and 15 percent of all stones are struvite.

Struvite stones are found more often in women and those who are over the age of 50. Unfortunately, even after these stones have been removed, about 10 percent of patients get recurring stones. In some cases, fragments of stones are left following treatment. These individuals face a much higher chance of getting the full-blown stones again. Studies show that people who get struvite stones a third time and are treated in a conservative manner (not surgery) could face renal failure, pyelonephritis, and sepsis. Pyelonephritis is severe inflammation of the kidney tissue. There are rare cases where chronic inflammation and infection can lead to cancer, which comes with a very poor prognosis.

What causes struvite kidney stones?

Kidney stones are formed from crystals. Normally, urine is slightly acidic, but if a person has a bacterial infection, the urine becomes more alkaline. This is due to the fact that bacteria can convert urea in the urine into ammonia. Ammonia raises alkaline pH in urine. There are minerals in urine that just do not dissolve in alkaline urine, so they build up into crystals. So in a nutshell, this is what causes struvite kidney stones.

As mentioned above, struvite stones are a combination of ammonium, magnesium, and phosphate mineral. They develop when urine is alkaline, which generally happens during a bacterial infection or soon after an infection. There are a number of different bacteria that can lead to the formation of stones, including staphylococcus, hemophilus species, klebsiella species, and pseudomonas, to name a few. Yeast can also cause struvite stones. Cryptococcus species, Rhodotorula species, Sporobolomyces species, and Candida humicola are among the yeast that can lead to the formation of stones.

What are symptoms of struvite kidney stones?

While struvite kidney stones share many of the symptoms associated with other types of kidney stones, there are additional signs to watch for. Below is a list of struvite kidney stones symptoms that a person might experience.

  • Abdominal pain: This pain is best described as a burning sensation, although some people also experience cramping. Struvite related pain tends to be less localized and dull.
  • Back pain: Lower back pain is common in those suffering from kidney stones.
  • Blood in urine: There are situations where the stones can damage the inner lining of the urinary tract, which can cause blood in the urine. Urine can also take on a cloudy appearance and foul odor.
  • Weight loss: A large stone and chronic urinary tract infection can cause weakness and weight loss.
  • Fever, chills, nausea: Research shows that struvite stone symptoms are similar to typical infections and can include fever, chills, nausea, as well as loss of appetite.

Complications of struvite kidney stones

Struvite kidney stones are not without complications. For instance, infectious problems can occur with non-invasive or invasive treatment. Infections tend to happen early after what is known as Percutaneous nephrolithotomy or PNL, which is a minimally-invasive procedure to remove kidney stones by making a small puncture wound through the skin. Detecting a bleed following PNL is very important. Those who undergo Shock Wave Lithotripsy or SWL, a treatment that uses shock waves from outside the body to target the stones and cause them to fragment, have lower risks.

Here is an overview of potential complications associated with struvite kidney stones:

  • Need for blood transfusions
  • Post-op or post-procedure infections
  • Adjacent organ injury (spleen, colon, liver)
  • Infundibular pulmonary stenosis (obstruction of outflow from the right ventricle)
  • Sepsis/pyelonephritis, which can lead to renal failure
  • Perforation of the renal pelvis
  • Low sodium level (hyponatremia)
  • Low body temperature (hypothermia)
  • Loss of kidney
  • Vascular injury
  • Neurogenic bladder (nerves of the urinary system fail)
  • Urinoma (urine leakage)
  • Death

Treating struvite kidney stones

Struvite kidney stone treatment can be categorized as medical or surgical. There are certain circumstances where surgery is recommended. For instance, a staghorn kidney stone is a large stone that spans more that one branch of the renal pelvis and usually requires surgical removal.

Medical treatment:

  • Antibiotics: Suppressive antibiotic therapy has been known to prevent pyelonephritis and associated infections. It may lower chances of stone growth.
  • Diet: Although it has had only modest success, a diet of low-phosphorus, low calcium, and aluminum hydroxide gel has been used to treat struvite stones. Dietary research as it pertains to kidney stones is ongoing.
  • Unease inhibitors: Can penetrate the bacterial cell wall and acts in concert with many antibiotics. AHA is the most used inhibitor, but the American Urological Association suggests acetohydroxamic acid only be used after surgical options have not worked well for a patient.
  • Pain relievers: In situations where stones are small, pain relievers are often suggested to deal with the discomfort. Advil, Motrin IB, Aleve, and Tylenol are common pain relievers.

Surgical treatment:

  • Extracorporeal shockwave lithotripsy: SWL was developed in the early 80’s and used to turn stones into fragments without the need for an incision. Some patients require multiple sessions.
  • Percutaneous nephrolithotomy: PNL is a renal collecting system that allows for the use of a nephroscope to fragment and remove stones. Today, flexible scopes, along with laser fibers allow for access to the kidney for easier stone destruction.
  • Laser and electrohydraulic ureteroscopic lithotripsy: This is an advancement in technology that allows for instruments to reach the kidney from the opening of the urethra.

It is worth noting that between 70 and 90 percent of typical crystals are tiny enough to travel through the urinary tract and leave the body in the urine without even being noticed. In other words, no treatment is required.

Diet for struvite kidney stones

Eliminating infection and lowering the chances of new struvite stones forming can be accomplished with a struvite kidney stones diet. The list below outlines some of the dietary steps to take into consideration if you are concerned about kidney stones.

  • Drink water: Plenty of water can flush out bacteria, which can be responsible for urinary tract infections. Never let yourself become dehydrated.
  • Drink cranberry juice: This juice is known to help flush out infective pathogens, particularly during an infection. Coconut water and beer are also known for flushing out stones.
  • Avoid magnesium-rich foods: Foods such as peanuts, spinach, tofu, and almonds should not be consumed in large amounts.
  • Try watermelon seeds: These seeds are a natural diuretic, known to help flush out particles of stones from the kidney. They also help remove bacteria that stick to the walls of the urinary tract organs.
  • Consume rosemary and agrimony: These herbs are useful in reducing the formation of new stones.
  • Reduce sodium: High amounts of sodium can increase urinary saturation of calcium phosphate and monosodium rate, increasing the risk of kidney stones.
  • Increase fiber: Bran, whole grains, green leafy vegetables, beans, and fresh fruits are a good option for optimal kidney health.
  • Add B-complex vitamin: A deficiency in vitamin B-6 and B-1 has been linked to the formation of kidney stones.
  • Control sugar intake: A high sugar diet is associated with kidney stones.
  • Consider vegetarian meals: Research suggests that plant sources of oxalates and calcium do not cause kidney stone formation, but animal protein can help in the forming of stones.
  • Consume high citrate foods: Struvite stones dissolve in acidic urine. Fruits and juices fall into this category of foods.
  • Supplement with vitamin C: Studies show that vitamin c is helpful in warding off infection and the formation of kidney stones.

Prognosis of struvite kidney stones


While many stones do pass on their own, unfortunately, this is not the case 100 percent of the time. While treatment for kidney stones can be very important, patients also want to know what the chances are of having to go through that excruciating pain again.

Research suggests that residual fragments occur in anywhere between 22 and 70 percent of patients and that further treatment is needed in 32 to 88 percent of patients. Studies also indicate that 86 percent of patients with small stone fragments who received treatment with SWL and antibiotics were able to avoid chronic infections. It is important to know that being stone free doesn’t mean that you won’t ever have a urinary infection again.

It is true that kidney stones can have frightening consequences, but in the majority of cases, they pass or can be treated without any long-lasting negative impact. Keep in mind that kidney stones can still be a serious health risk. In addition to being painful, kidney stones can cause permanent damage to your kidney and result in death. Kidney failure and death do not happen nearly as often as it used to due to advances in medical diagnosis and stone removal, but the key is receiving treatment before permanent damage occurs.



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