Understanding the Different Types of Kidney stones Urology Specialists

What doctors refer to as “nephrolithiasis”, you might know as kidney stones.

Kidney stones are hard mineral based masses that typically form in the kidneys or urinary tract and cause an immense amount of pain. About 90% of stones can be treated to pass through the system on their own, but some are too large and will require surgery to remove.  

By understanding the four different types of kidney stones and their causes, you will be able to make smarter lifestyle and diet choices in order to prevent them.

The 4 Different Types of Kidney Stones

Calcium Stones

The most common kidney stone is a calcium stone.

Generally, a calcium stone consists of calcium oxalate, but can sometimes consist of calcium phosphate or maleate.

Oxalate is a natural substance found in certain fruits, veggies, nuts, and chocolates. Once your body takes what it needs from these foods, the waste (including the oxalate) will pass through the bloodstream to the kidneys where it becomes urine. Typically this is where calcium will bond with oxalate and together they will leave the body.

But, if during this process there isn’t enough liquid present (or a few other circumstances), the oxalate can crystallize, stick to calcium, and form a stone.


  • Obesity
  • Dehydration
  • Certain medical conditions like dent disease and hyperparathyroidism
  • Digestive diseases and digestive system surgeries
  • Anything that increases the amount of calcium or oxalate in your urine

Uric Acid Stones

Uric acid stones are the second most common of the stones, making up about 10% of all kidney stones.

Crystallization and the formation of uric acid stones occur most often when urine pH is too low.

Luckily, you can almost always be successfully dissolve uric acid stones by increasing hydration or undergoing a urine alkalinization treatment to bring urine pH levels up.


  • Low urinary volume
  • Obesity or diabetes
  • Chemotherapy treatments
  • Persistently low urinary pH
  • A high purine diet (found in animal proteins like beef, poultry, pork, eggs, fish)
  • Inherited problems that affect how the body processes uric acid or protein (for example gout or congenital hyperuricemia)


A little more than 10% of kidney stones are struvite, and this type of stone is more commonly found in women than men.

When a person has a bacterial infection such as a urinary tract infection, normally acidic urine becomes more alkaline. This is because bacteria converts urea into ammonia which raises alkaline pH in the urine. Minerals including ammonia, magnesium, and phosphate cannot dissolve in alkaline urine so they crystallize and form struvite stones.

Struvite stones grow large very quickly and block your kidney, ureter, or bladder. It’s important to treat them before the causes damage to your kidneys or leads to a life-threatening infection.  


  • Bacteria including staphylococcus, Haemophilus species, Klebsiella species, and Pseudomonas
  • Yeasts including Cryptococcus species, rhodotorula species, sporobolomyces species, and candida humicola

Cystine Stones

Cystine stones are caused by a hereditary disorder called cystinuria. The disorder is rarely diagnosed as both parents must pass down the gene. It’s estimated that 1 in 7,000 people worldwide have Cystinuria.  

Cystinuria causes the natural substance of “cystine” to leak into your urine. When there is too much cystine in the urine, stones will form.

While it’s possible to manage these stones, they cannot go away completely.


  • Cystinuria (an inherited condition)

The types of kidney stones and their causes may vary, but the one thing they all have in common is the amount of pain they cause. It’s important to be able to recognize the symptoms associated with kidney stones in order to detect them early on.


There are several overarching preventive measures you can take to prevent kidney stones in general from developing.

  • Limit protein, sodium, and sugar intake
  • Consume the daily recommended amount of calcium to keep oxalate levels normal.
  • Regularly exercise and practice portion control for overall health
  • Discuss medications with your doctor as some can cause stones to form
  • Drink plenty of fluids (ideally water) to keep stone-forming minerals and/or bacterias from settling in the kidneys and producing stones

We diagnose kidney stone and perform procedures and treatments regularly in our offices. If you think you might be experiencing symptoms of kidney stones set up an appointment with a specialist in one of our offices.