Kidney stones form when substances in urine become concentrated enough to form crystals. These crystals can grow and join together, eventually creating a stone.
There is usually more than one contributing factor. Fluid intake, diet, inherited tendencies, medical conditions, and certain medicines can influence the conditions in which stones develop.
Understanding your risk factors helps guide prevention. However, your symptoms or the foods you recently ate cannot reliably reveal what a stone is made of.
Affiliate disclosure: We may earn a commission if you purchase through links in this article.
For optional reading alongside medical advice, view the Kidney Stone Removal Report. It is an information product and cannot identify the underlying cause of your stones or replace appropriate testing.
How Do Kidney Stones Form?
Urine normally contains dissolved substances such as calcium, oxalate, and phosphorus. Their presence is not automatically a problem.
When the balance changes, some substances can crystallize instead of remaining dissolved. The amount of water in urine and its chemical environment influence this process.
This is why two people with similar diets may have different stone risks. The important question is not simply whether a food contains a particular mineral, but how the person’s body processes it and what happens in their urine.
Common Kidney Stone Risk Factors
| Risk factor | How it can contribute |
|---|---|
| Low urine volume | Leaves stone-forming substances more concentrated |
| High sodium intake | Can increase calcium excretion in urine |
| Certain dietary patterns | May affect calcium, oxalate, uric acid, and other urinary factors |
| Previous stones or family history | Can indicate a greater tendency to form stones |
| Digestive conditions or surgery | May change fluid balance or absorption of stone-forming substances |
| Metabolic or hormonal conditions | Can alter urine chemistry or mineral levels |
| Certain urinary infections | Can promote infection-related stones |
| Some medicines and supplements | Can change urine chemistry or occasionally crystallize themselves |
These factors do not affect everyone equally. Their significance depends on the stone type and the individual’s test results.
1. Low Urine Volume and Fluid Loss
Not drinking enough to replace fluid losses can reduce urine volume. With less fluid available, stone-forming substances become more concentrated.
Risk may increase during hot weather, heavy sweating, or other situations involving substantial fluid loss. Drinking habits should account for those circumstances.
For practical guidance, read how much water to drink for kidney stone prevention.
If you have a prescribed fluid restriction, ask your clinician about an appropriate target. A general prevention recommendation should not override your medical instructions.
2. Dietary Factors
Too Much Sodium
A high-sodium diet can increase the amount of calcium entering urine. Sodium comes from more than table salt: packaged meals, sauces, processed meats, and restaurant foods may contribute substantially.
Large Amounts of Animal Protein
Higher animal-protein intake can contribute to stone risk in susceptible people. Whether you need to change your intake depends on your stone type and overall nutritional needs.
Oxalate and Calcium Balance
Oxalate is relevant to calcium oxalate stones, but it does not mean everyone needs to avoid every oxalate-containing food.
Cutting dietary calcium too low can also be counterproductive. Calcium consumed with food can bind oxalate in the digestive tract, reducing its absorption. Calcium in food and calcium supplements should not be treated as interchangeable decisions.
Our kidney stone diet plan covers food choices in more detail. Avoid starting a highly restrictive diet before you know which changes are appropriate.
3. Family History and Previous Stones
Having a close relative with kidney stones increases your likelihood of developing them. A previous stone also makes future episodes more likely.
Some people have specific inherited disorders. For example, cystinuria causes excess cystine in urine and can lead to cystine stones.
Tell your clinician if:
- Stones began during childhood or early adulthood.
- Several relatives have experienced stones.
- You have repeated episodes.
- Previous stones were identified as an unusual type.
These details help the clinician decide how extensively to investigate.
Read our recurrent kidney stone guide for the next steps after repeated episodes.
4. Digestive Conditions and Weight-Loss Surgery
Inflammatory bowel disease, chronic diarrhea, and certain intestinal or weight-loss operations can increase stone risk.
Changes in digestion and absorption may increase the amount of oxalate reaching the urine. Ongoing diarrhea can also contribute to fluid loss.
Mention any bowel disease or surgery during your assessment, even if it happened years ago. It may help explain why general dietary advice has not been enough.
5. Medical Conditions That Affect Urine Chemistry
Conditions associated with increased stone risk include:
- Diabetes and metabolic syndrome.
- Gout.
- Hyperparathyroidism.
- Certain kidney disorders.
These conditions influence risk through different mechanisms. For example, hyperparathyroidism can disturb calcium regulation, while diabetes is associated with a greater likelihood of uric acid stones.
Having one of these conditions does not establish your stone type. It provides a reason to investigate rather than a diagnosis based on association alone.
If you explore the Kidney Stone Removal Report, discuss any proposed changes with your clinician. An underlying medical condition may require a more specific prevention plan.
6. Certain Urinary Tract Infections
Some bacteria change urine chemistry in a way that encourages struvite stones to form.
This does not mean every urinary tract infection produces a stone, or that every stone is caused by infection. Infection-related stones require medical assessment and treatment.
Our struvite kidney stone guide explains this relationship.
Fever or chills with suspected kidney stone symptoms require urgent assessment, especially when urine flow may be blocked.
7. Medicines and Supplements
Some medicines increase stone risk by changing urine chemistry. Others can occasionally form crystals from the drug or its breakdown products.
Examples include topiramate, acetazolamide, and certain HIV medicines. Some supplements may also affect risk depending on the dose and the person’s circumstances.
Do not stop a prescribed medicine on your own. Ask your prescriber or pharmacist whether it is relevant to your stone history and whether monitoring or an alternative is appropriate.
Bring a complete list that includes:
- Prescription medicines.
- Over-the-counter products.
- Vitamins and minerals.
- Herbal products.
- Sports or weight-loss supplements.
See our medications that increase kidney stone risk guide. Although written with older adults in mind, medication review can matter at other ages too.
Why the Stone Type Matters
Different stones can develop under different conditions.
| Stone type | Examples of relevant factors |
|---|---|
| Calcium oxalate | Urinary calcium and oxalate, fluid balance, diet, and inherited or medical factors |
| Calcium phosphate | Urine chemistry, including a higher urine pH |
| Uric acid | Persistently acidic urine and associated metabolic factors |
| Struvite | Certain urinary infections |
| Cystine | An inherited condition called cystinuria |
A person can also have a stone containing more than one material. The label “kidney stone” therefore does not identify one universal cause.
For a fuller explanation, read the different types of kidney stones.
How Can You Find Your Own Risk Factors?
An individualized assessment may include your medical and family history, medicines, blood tests, and urine tests.
If a stone is recovered, laboratory analysis can identify its composition. Selected patients may also benefit from a 24-hour urine assessment to investigate factors contributing to recurrence.
Useful questions to ask include:
- Was my stone analyzed?
- Which risk factors appear relevant to me?
- Do I need further blood or urine testing?
- Should any medicines or supplements be reviewed?
- Which prevention changes should I prioritize?
The goal is to identify actionable factors rather than blame one meal or habit.
Frequently Asked Questions
Are kidney stones always caused by dehydration?
No. Low urine volume is an important contributor, but diet, genetics, medical conditions, infections, and medicines may also matter.
Does eating calcium cause calcium stones?
Not automatically. Adequate calcium from food can help limit oxalate absorption. Do not eliminate calcium-rich foods simply because your stone contains calcium.
Can healthy eaters still develop kidney stones?
Yes. Dietary choices are only part of the picture. A family tendency or an underlying medical condition can remain relevant even with a balanced diet.
Can symptoms tell me why my stone formed?
No. Symptoms may suggest a stone episode, but they do not reliably establish the underlying cause or composition. Testing and stone analysis provide more useful information.
Should everyone follow the same prevention plan?
No. The most appropriate changes depend on the stone type, test results, medical conditions, and medicines. Use the linked prevention guides to prepare questions for your clinician.
Optional further reading: Kidney Stone Removal Report. Purchasing a report is not necessary to receive appropriate testing or personalized prevention advice.
Resources
- NIDDK: Symptoms and Causes of Kidney Stones
- NIDDK: Definition and Facts for Kidney Stones
- NIDDK: Eating, Diet, and Nutrition for Kidney Stones
- National Kidney Foundation: Kidney Stones
- European Association of Urology: Metabolic Evaluation and Recurrence Prevention
- MedlinePlus: Kidney Stone Analysis
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Medical disclaimer: This article provides general information and does not replace personalized medical advice, diagnosis, or treatment. Do not stop prescribed medicines or make major dietary changes without appropriate professional guidance.