What Causes Struvite & Staghorn Kidney Stones?

Kidney stones or renal calculi are deposits of salts and mineralized substances that crystallize within the kidney, ureters, or bladder. Kidney stones are ranked highest on the pain scale as they create a blockage in the urinary tract and cause inflammation.

A variety of factors contribute to kidney stone formation. A poor diet, insufficient water consumption, regular calcium and oxalate intake, phosphate levels, a history of kidney stones, and urinary tract infections are all contributors to an increased risk of developing kidney stones. 

When unchecked, kidney stones can lead to serious conditions such as kidney infections, renal failure, and even cancer of the kidneys. Struvite stones are often the result of urinary tract infections. Staghorn kidney stones, on the other hand, are much larger and also find root in urinary tract infections and affect large parts of the tubes of the kidneys transporting urine.

In this article, we look at various kidney stones, their causes, and what you can expect in terms of treatment and management. 

How are Kidney Stones Formed?

When the body persistently produces highly concentrated urine or urine high in oxalate, uric acid, phosphate, or mineral content, small mineralized crystals are formed. They tend to clump together due to low water content, forming larger clumps. These clumps eventually form kidney stones found in the kidneys or urinary tracts.

Types of Kidney Stones & Their Causes 

Some of the common types of kidney stones are: 

  • Calcium Stones: These are by far the most common forms of kidney stones, and are often made of calcium oxalate crystals. Lower water intake, high levels of urine calcium, and excessive consumption of oxalate-rich foods like tomatoes, chocolates, eggplants, peanuts, beets, and spinach are responsible for calcium stones.
  • Struvite Stones: These stones develop from urinary tract infections and are most commonly found in women. Unaddressed infections lead to the formation of struvite stones. They are made of magnesium ammonium phosphate and are formed by the combination of phosphate and ammonium salts. Struvite stones are also known as triple phosphate stones and can be prevented by addressing urinary tract infections in time. 
  • Staghorn Stones: These kidney stones are also formed due to unaddressed urinary tract infections. However, staghorn kidney stones and calculi can develop from smaller struvite stones. These stones can grow large enough to block some of the main tubules of the kidney, known as calyces, which transport urine to the ureter and lower parts of the urinary canal. These stones can cause chronic blockage of the urinary tract, inflammation & infection of the kidneys, and even serious, life-threatening conditions like pyelonephritis. 
  • Uric Acid Stones: These kidney stones are caused by acidic urine in people that have a history of gouty arthritis. These kidney stones can occur either due to low water intake, improper uric acid metabolism, renal acidosis, or excessive intake of proteins. People suffering from chronic diarrhea, uncontrolled diabetes, and malabsorption syndrome are also at a high risk of contracting this condition. 
  • Cystine stones: These kidney stones are rare and only found in individuals suffering from a heritable metabolic disorder called cystinuria. The condition hampers the metabolism of the amino acid cystine and causes the kidneys to excrete this amino acid into urine. This causes crystallization of the amino acid and other mineral components, leading to cystine stones. 

what causes staghorn kidney stones

Predispositions & Risk Factors for Struvite & Staghorn Kidney Stones

Below are the main factors that can cause an increased risk to struvite stones and staghorn kidney stones: 

  • Decreased Hydration: Low water intake has been one of the most implicated causes in developing kidney stones. 
  • Reduced Urine Synthesis: People with metabolic problems, renal infections, systemic diseases affecting the kidneys, and liver disease are more likely to develop calculi like struvites and staghorns due to reduced urine production.
  • Sex: Though men are at a greater risk of developing kidney stones when compared to women, women are at a higher risk of developing struvite calculi and triple phosphate stones. 
  • Systemic Disease & Infections: Most struvite and staghorn kidney stone causes are linked to persistent or unresolved urinary tract infections in women. Inflammatory conditions like irritable bowel syndrome, celiac disease, hormonal imbalances such as hyperparathyroidism, metabolic conditions like diabetes, high urine calcium, and surgeries such as gastric bypasses increase your risk of developing renal stones. 
  • Age: The general age spectrum of developing renal calculi is 20-50. However, struvite kidney stones and staghorn calculi usually develop in those over fifty. 
  • Diet: A diet high in components like oxalates, minerals like phosphates, protein content, and salt can increase the risk of contracting renal stones. 
  • Lifestyle: Individuals that are prone to living a sedentary lifestyle and are obese are at greater risk of suffering from struvite kidney stones and staghorn calculi. 
  • Medication: Calcium and magnesium-based antacid salts, drugs like phenytoin used for epileptic seizures, and potassium & sodium-based diuretics for high blood pressure have all been known to increase chances of renal calculi, including struvite kidney stones and staghorn kidney stones. 

Symptoms of Kidney Stones

Struvite and staghorn kidney stone symptoms are similar to those of regular kidney stones. A few symptoms of these kidney stones are: 

  • Painful urination 
  • Severe pain on the side of your abdominal region and your back
  • Blood in your urine 
  • Foul-smelling urine 
  • Urine that appears cloudy 
  • Fever and chills 
  • Frequent low quantity urination 

kidney stone symptoms

Detection of Struvite & Staghorn Kidney Stones

To help your doctor diagnose struvite stones and triple phosphate stones, they will recommend a complete physical examination, a detailed personal, medical & family history, and any of the following diagnostic tests:

  • Blood tests that look for levels of calcium, phosphate, sodium, magnesium, and uric acid. 
  • A complete urine examination. 
  • Blood urea nitrogen. 
  • Chemical testing and examination of stones you may have passed before. 
  • Ultrasonography of the abdomen. 
  • CT scans 
  • MRIs
  • X-rays of the abdomen 
  • Retrograde and intravenous pyelograms 

Staghorn & Struvite Kidney Stones Treatment

The treatment options for both staghorn kidney stones and struvite kidney stones are similar to conventional renal calculi. They include:

  • Medical management: A regimen of antibiotics and painkillers to manage potential infections and pain arising from the stones. 
  • Percutaneous nephrolithotomy: This is a minor surgery that involves the removal of the calculi causing unmanageable blockage through a small incision on the back. 
  • Ureteroscopy: A small tube is inserted through the urethra to access the urinary bladder and ureters to help relieve any stones stuck in these regions. 
  • Lithotripsy: This is an advanced, relatively non-invasive procedure that uses targeted sound waves at high frequencies to help break up the stone into smaller, passable calculi.
  • Surgery: If none of the above modalities apply to the kind of staghorn and struvite kidney stones you have, your doctor will recommend surgery to remove them. 

kidney struvite stones treatment

Prevention & Takeaway

As is the norm, preventing a condition is far easier than curing it. As far as staghorn and struvite kidney stones are concerned, there’s not much to prove the effectiveness of most treatment regimens since their primary cause stems from infections. However, a healthy intake of citrates can help prevent most kidney stones. Make sure to never ignore a urinary tract infection and drink at least over 12 cups of water per day to improve and maintain urinary and renal health. Be sure to reach out to your healthcare provider if you encounter any symptoms or have further concerns regarding renal calculi.