Why Do Kidney Stones Form?

Последнее обновление: Август 30, 2026

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Kidney stones are among the commonest problems I see. Reported lifetime risk is at least 10% in US and European populations, and figures as high as 17% have been reported in this region — a difference that is itself a clue to what causes them. This article explains why stones form.

There is no single answer, because stone formation is multifactorial. The starting point is what the kidney does: it filters waste products from the blood and excretes them in urine. That makes the kidney the one place in the body where ions such as calcium, phosphate, uric acid and oxalate are routinely concentrated. When their concentration climbs high enough, they crystallise — and a stone begins.

Before the causes: the one situation that is an emergency

This article is about prevention, which is a calm subject. Stone disease has one situation that is not, and it is worth knowing before the rest.

A stone that blocks the drainage from a kidney is uncomfortable. A stone that blocks a kidney и that kidney becomes infected is a different matter entirely: the infection is trapped behind the blockage with nowhere to go, and a previously well person can become dangerously ill within hours. It is one of the few true emergencies in urology, and the treatment is to drain the kidney urgently rather than to wait for antibiotics to work.

Go to an emergency department the same day — in Thailand you can call 1669 — if you have:

• Fever or shaking chills together with flank or back pain, whether or not you know you have a stone. This is the one on this list that matters most.
• Pain that painkillers are not controlling, or persistent vomiting that stops you keeping fluids down.
• Passing little or no urine, or feeling faint, confused or generally very unwell.
• Any stone pain if you have only one working kidney, or a kidney transplant, since there is no second kidney to compensate while the situation is assessed.

1. Host factors — the ones you cannot change

• Family history — and this one is stronger than most patients expect. Twin and family studies put the heritability of stone disease at roughly 46–63%, and having a parent or sibling who forms stones raises your own risk by about three-fold. It is one of the strongest predictors of recurrence there is. In a minority of cases the cause is a single identifiable gene — found in around 10% of adults and up to 30% of children with stones — which is why stones starting in childhood or early adulthood deserve a proper metabolic work-up rather than general advice. Mention your family history at your appointment; it is often what tips the balance towards investigating your chemistry properly.
• Ethnicity and region — lifetime risk is around 10–15% in developed countries but 20–25% in the Middle East, and within this region north-eastern Thailand and Cambodia are recognised as high-stone areas. What is not settled is how much of that is genetic and how much is diet, climate and hydration, which travel together with geography and are extremely difficult to separate. Large genetic studies across different populations have found broadly similar genetic architecture, so regional differences should not be read as primarily inherited. The honest position is that both contribute and the balance is unresolved.
• Sex — men are affected more than women, at a ratio of roughly 2:1 worldwide.
• Возраст — the peak is between 40 and 60.
• Existing medical conditions — obesity and diabetes are reported to raise the risk by around 55% and 59% respectively. Both increase the amount of stone-forming ions excreted in the urine. Unlike the items above, these two are modifiable, which makes them worth acting on.

2. Экологические факторы — the ones you can

• Climate — incidence is higher in tropical regions. People in hot climates lose fluid through sweat, pass less urine, and so concentrate their urinary ions further. This is the likeliest explanation for the regional differences above.
• Fluid intake — the single easiest way to reduce risk. Every additional 500 mL of water a day significantly lowers the incidence, and around 2,500 mL daily is the usual recommendation for stone prevention. Anyone with heart or kidney disease, or on fluid restriction for another reason, should agree their target with their own doctor first.
• Диета — high sodium, high oxalate, high-dose vitamin C supplements and unbalanced calcium intake all push the risk up, as does a diet heavy in animal protein, which raises urinary uric acid. Note that cutting dietary calcium is usually the wrong move: it tends to increase oxalate absorption and can make stones more likely rather than less.
• Too little citrate — citrate is a natural stone inhibitor, and citrus fruits are rich in it. A glass of lemon juice a day is a reasonable measure for anyone concerned about stones; where more is needed, potassium citrate therapy is the medical version of the same idea.
• Some medications and supplements — a number of prescribed medicines raise stone risk, and calcium or vitamin D supplements taken without a reason can do the same. Bring a list of everything you take to your appointment rather than assuming it is irrelevant, and do not stop a prescribed medicine on your own account.

Kidney stone disease is sometimes described as a metabolic disease rather than a plumbing problem, because so much of what drives it is happening in the body’s chemistry rather than in the kidney itself. That framing is useful for patients: it explains why stones tend to come back if nothing changes, and why prevention is built out of daily habits rather than a single procedure. Look again at the second list — every item on it is something you can act on.

What a prevention plan actually involves

General advice suits most people who have had one stone. Where stones keep returning, where they start young, where there are several at once or in both kidneys, or where there is a strong family history, the useful next step is to stop guessing and measure. That usually means three things together: analysing the stone itself, a blood test looking at kidney function, calcium, uric acid and related chemistry, and a collection of urine over a full day to see what is actually being excreted and in what concentration.

That is what turns advice into a plan. It can reveal a specific, treatable reason for the stones — an overactive parathyroid gland, a problem with how the kidney handles acid, gout, a bowel condition affecting absorption, or repeated infection producing a particular kind of stone — and each of those has its own treatment rather than being helped by drinking more water alone. It is worth asking for if you have been through the same advice more than once and are still forming stones.

One practical note for anyone who has already passed a stone: keep it and take it to your urologist. Knowing what the stone was made of is what turns general prevention advice into a plan aimed at your particular chemistry. A stone caught in a strainer and put in a clean container tells us more than most scans.

Если у вас часто образуются камни в почках или вы хотели бы получить индивидуальный план профилактики, доктор Соарави Веерасопоне проводит консультации специалистов в Главном госпитале Бангкока. Записаться на консультацию. Записаться на прием в больницу Самититедж Сирача можно, позвонив в отделение урологии по телефону 088-022-1445. Questions about the cost of consultation, testing or treatment should go to the hospital directly — for Bangkok Hospital, by email to bhquro@bdms.co.th.

Prevention planning suits a video consultation particularly well, since it is built from your history, your previous imaging and your test results rather than from an examination. Bangkok Hospital runs a Telemedicine service, arranged in advance by email to the Urology department at bhquro@bdms.co.th — send any previous stone analysis, scan reports and blood results with the request. Acute stone pain is a different matter and should be seen in person, or in an emergency department if any of the warning signs above apply. Samitivej Sriracha is in-person only.

Часто задаваемые вопросы о образовании камней в почках

Отказ от ответственности: This content is written and reviewed by Dr. Soarawee Weerasopone, a board-certified urologist at Bangkok Hospital Headquarters. It is intended for educational purposes only and does not constitute medical advice. Fluid targets and dietary changes need adjusting for your own kidney and heart health, and no prescribed medicine should be stopped on the basis of this article. No medical advice, diagnosis or prescription is provided through personal messaging channels or social media. Always consult a qualified healthcare professional before starting any medical treatment. In an emergency, attend the nearest emergency department — in Thailand the emergency number is 1669.