Not all kidney stones are the same. They can look different, form for different reasons, and require different prevention strategies. Knowing your stone type is one of the most important pieces of information you can have if you have ever passed a stone — it shapes almost every step of prevention.
In this guide, we break down the five main types of kidney stones: what they are, why they form, who is most at risk, and how each type is typically managed.
Why Stone Type Matters
Different stones respond to different treatments. For example, calcium oxalate stones respond to changes in fluid, sodium, and dietary calcium. Uric acid stones can often be dissolved by making the urine less acidic. Struvite stones are almost always tied to infection, and cystine stones are the result of an inherited condition.
The only way to know your exact stone type is to have a passed or removed stone analyzed in a lab. Blood and 24-hour urine testing can strongly hint at the likely type as well.
The 5 Main Types of Kidney Stones
| Stone Type | Approximate Share | Main Drivers |
|---|---|---|
| Calcium Oxalate | ~70–80% | Dehydration, high oxalate, low calcium at meals, high sodium |
| Calcium Phosphate | ~10–15% | High urine pH, certain metabolic conditions |
| Uric Acid | ~5–10% | Acidic urine, high animal protein, gout, obesity |
| Struvite | ~5–10% | Chronic urinary tract infections |
| Cystine | <1% | Inherited disorder (cystinuria) |
1. Calcium Oxalate Stones
Calcium oxalate is by far the most common kidney stone type. It forms when calcium binds with oxalate in the urine instead of the gut, creating hard crystals.
Who is at risk?
- People with low fluid intake
- Those with high-sodium, high-animal-protein diets
- People who avoid dietary calcium
- Those with high-oxalate diets
- People with gut conditions like IBD or a history of bariatric surgery
How they are prevented
- Plenty of fluids — enough to produce 2 to 2.5 liters of urine per day
- Adequate dietary calcium (paired with oxalate at meals)
- Moderate sodium intake
- Moderate animal protein intake
- Awareness of very high-oxalate foods (spinach, rhubarb, almonds, beets)
For a complete dive into this type, see our detailed guide to calcium oxalate stones.
2. Calcium Phosphate Stones
Calcium phosphate stones are less common than oxalate stones and tend to form when the urine is more alkaline. They are often linked to specific medical conditions such as renal tubular acidosis, hyperparathyroidism, and certain kidney disorders.
Who is at risk?
- People with elevated blood calcium (from parathyroid issues or other causes)
- Those with metabolic conditions that raise urine pH
- People taking certain medications long term
How they are managed
- Treating the underlying medical condition
- Adjusting fluids and diet based on 24-hour urine results
- Medications when needed to correct urine chemistry
3. Uric Acid Stones
Uric acid stones form when the urine is consistently too acidic. They are strongly linked to diets high in animal protein (especially organ meats and shellfish), obesity, gout, diabetes, and certain metabolic syndromes.
Who is at risk?
- People with gout or high uric acid levels
- People with diabetes or metabolic syndrome
- Those on very high animal-protein or ketogenic diets
- People with chronic diarrhea (which acidifies urine)
How they are prevented
- Increased fluid intake
- Moderating animal protein
- Weight and metabolic health management
- Making the urine less acidic — often with potassium citrate
- Sometimes allopurinol to lower uric acid
A unique feature of uric acid stones: they can sometimes be dissolved with medication that raises urine pH.
4. Struvite Stones (Infection Stones)
Struvite stones form as a direct result of certain urinary tract infections — specifically those caused by bacteria that produce an enzyme called urease. They can grow quickly and become very large, sometimes filling entire portions of the kidney (called "staghorn" stones).
Who is at risk?
- People with chronic or recurrent urinary tract infections
- People with urinary catheters
- Those with anatomical urinary tract issues
- People with spinal cord injuries or neurogenic bladder
How they are managed
- Treating and eliminating the underlying infection
- Removing or breaking up the stone (often surgically)
- Long-term monitoring and infection prevention
Struvite stones require medical treatment. Dietary changes alone will not solve them.
5. Cystine Stones
Cystine stones are rare and caused by an inherited condition called cystinuria, in which the kidneys allow too much cystine — an amino acid — to leak into the urine. Cystine crystallizes when its concentration in urine is too high.
Who is at risk?
- People with a family history of cystinuria
- Individuals diagnosed with the condition, often in adolescence or early adulthood
How they are managed
- Very high fluid intake — often more than 4 liters per day
- Medications that raise urine pH and reduce cystine solubility
- Specific medications like tiopronin in some cases
- Regular monitoring and imaging
Mixed Stones and Rare Types
Some stones contain more than one type of crystal — for example, a calcium oxalate stone with a smaller calcium phosphate component. Rare stones can also form due to medications (drug-induced stones), specific metabolic disorders, or unusual dietary patterns.
Diagnosing Your Stone Type
Doctors typically identify stone type using a combination of:
- Stone analysis after a stone is passed or removed
- Blood tests (calcium, uric acid, kidney function, parathyroid hormone)
- 24-hour urine collection
- Imaging characteristics on CT scan
- Clinical history (family history, gut health, infections, medications)
Why Personalized Prevention Matters
Different stone types can react in opposite ways to the same dietary change. For example:
- Cutting animal protein is helpful for uric acid stones but only mildly protective for calcium oxalate stones.
- Raising urine pH helps uric acid stones but may worsen calcium phosphate stones.
- Cutting calcium worsens calcium oxalate risk in most people.
That is why a general "kidney stone diet" is only a starting point. If you have had multiple stones, working with a urologist and a registered dietitian is often the best route to a plan tailored to your stone type.
References
- National Kidney Foundation — Types of Kidney Stones.
- National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK / NIH) — Kidney Stone Types.
- Mayo Clinic — Kidney Stones: Types and Diagnosis.
- Cleveland Clinic — Kidney Stones: Types and Composition.
- American Urological Association — Medical Management of Kidney Stones Guideline.
The Bottom Line
Kidney stones fall into five main types, each with different causes and different prevention strategies. If you have ever passed a stone, doing everything possible to have it analyzed is one of the most valuable things you can do for your long-term kidney health. Knowing your type turns generic advice into a plan that actually fits you.
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