Uric Acid Stones: The One Kidney Stone That Can Be Dissolved

อัปเดตล่าสุด: 28 สิงหาคม 2569

• เวิร์ดเพรส
• ลิงค์อิน
• จดหมาย

Patients ask constantly whether a kidney stone can be treated with tablets instead of surgery. For one stone type the answer is genuinely yes — a uric acid stone can be dissolved, not merely passed or prevented. No other common stone can.

The catch is in the first word. This only works if the stone actually is uric acid, which has to be established rather than hoped for.

• ศูนย์โรคทางเดินปัสสาวะ โรงพยาบาลกรุงเทพ ทำนัด Online 02-310-3009 bhquro@bdms.co.th
• โรงพยาบาลสมิติเวชศรีราชา ชลบุรี 088-022-1445

What stones are made of

• Calcium-containing stones — the large majority, around eight in ten.
• Uric acid stones — roughly one in ten, and the subject of this page.
• Infection stones and rarer inherited types — a small proportion, and managed differently again. Infection stones in particular can grow very large and generally need surgery, so they are worth knowing about.

The earlier version of this article said that calcium stones must be treated surgically. That is not right and has been corrected. Small calcium stones frequently pass on their own, small stones causing no trouble are often simply watched, and recurrence can be reduced substantially by diet and by medication. What is true is that a calcium stone cannot be dissolved — a different statement, and much less alarming. See do all kidney stones need treating.

Why uric acid stones form — and what they say about you

This was missing from the earlier version and it matters more than the treatment does.

Uric acid dissolves poorly in acidic urine. The usual reason someone forms these stones is not that they produce too much uric acid but that their urine is persistently too acidic — and that pattern travels with obesity, insulin resistance, type 2 diabetes and gout.

So a uric acid stone is worth treating as a piece of information as well as a problem. A man who forms one and has never had his blood sugar or weight addressed has been given a warning and a treatment; taking only the treatment wastes the warning. It also means the stones recur reliably if the underlying pattern is not tackled.

Establishing that it really is uric acid

• Suggestive: persistently acidic urine on testing, and a stone of characteristically low density on CT. Together these are a reasonable basis to try dissolution.
• Definitive: analysis of the stone itself in the laboratory — which requires catching it. If you have ever passed a stone and thrown it away, that is the single most useful thing that has been lost. Strain your urine and keep anything you catch, however small and unimpressive it looks.

For anyone forming stones repeatedly, blood and 24-hour urine testing identifies the metabolic drivers and is what turns treatment of this stone into prevention of the next one. See เหตุใดจึงมีนิ่วในไต.

The treatment

The whole approach rests on one idea: make the urine less acidic and the stone dissolves. The target is a urine pH of roughly 6.5 to 7.0, and you may be asked to test your own urine with pH strips at home.

• Urine alkalinisation, usually with potassium citrate. This is the main lever.
• Fluid — at least around 2.5 litres a day, enough that urine stays pale.
• Less animal protein — meat, and organ meats particularly — which both raises uric acid and acidifies urine.
• More fruit and vegetables. On citrus: the earlier version recommended orange juice and lemonade. Lemon juice diluted in water without added sugar is the version that raises citrate without the sugar load, and commercial lemonade and sweetened juices work against the metabolic problem underlying the stones in the first place.
• A uric acid-lowering drug such as allopurinol, where uric acid production is genuinely high or there is gout. It supports the alkalinisation rather than replacing it.

The caution that was not on this page

Potassium citrate is not a benign supplement. It raises blood potassium, which matters a great deal in two situations: impaired kidney function, and taking another drug that also raises potassium — several common blood pressure medicines and some diuretics do exactly that. High blood potassium is dangerous and causes no symptoms until it is serious.

Which is why this is a prescribed and monitored treatment with blood tests, not something to buy and start. Stomach upset is also common and often the reason people stop.

What to expect, honestly

• It takes weeks to months, not days, and requires taking the medication consistently. Progress is followed by repeat imaging showing the stone shrinking, alongside urine pH.
• Large stones dissolve less reliably than small ones.
• A stone stuck in the ureter and obstructing the kidney is not managed by waiting for it to dissolve. Obstruction is dealt with first; dissolution is a treatment for stones sitting in the kidney, not for a blockage.
• If it does not work, shockwave treatment or endoscopic laser surgery follow — and uric acid stones, being low density, are among the less suitable for shockwave, so endoscopic treatment is often preferred.

อาการที่ต้องไปพบแพทย์ในวันเดียวกัน

ในกรณีฉุกเฉินในประเทศไทย โทร 1669.

• Fever or shaking chills with flank pain. An obstructed kidney that becomes infected is an emergency requiring urgent drainage — antibiotics alone are not enough. This is the most dangerous thing on this page.
• Severe pain not controlled by the painkillers you have, or with persistent vomiting.
• Passing little or no urine, particularly with a single kidney or a transplant.
• Flank pain in pregnancy.

Frequently Asked Questions About Uric Acid Stones

Can a kidney stone really be dissolved with tablets?

A uric acid stone can. It is the only common type that dissolves, because uric acid is poorly soluble in acidic urine and becomes soluble when the urine is made less acidic — the target being a pH of roughly 6.5 to 7.0. It takes weeks to months and requires consistent treatment and monitoring.

How do I know my stone is the uric acid type?

Persistently acidic urine and a characteristically low-density stone on CT are suggestive. Analysis of the stone itself is definitive, which means catching it — strain your urine and keep anything you pass, however small.

Do calcium stones always need surgery?

No, and an earlier version of this article said so. Small calcium stones often pass on their own, small stones causing no problems are frequently just monitored, and recurrence can be reduced by diet and medication. What is true is that they cannot be dissolved, which is a different and far less alarming statement.

Is potassium citrate safe to just start taking?

No. It raises blood potassium, which is dangerous in impaired kidney function or alongside other drugs that raise potassium, including several common blood pressure medicines — and high potassium causes no symptoms until it is serious. It is prescribed and monitored with blood tests. Stomach upset is also common.

Why did I get a uric acid stone?

Usually because your urine is persistently too acidic rather than because you produce too much uric acid — a pattern strongly associated with obesity, insulin resistance, type 2 diabetes and gout. Dissolving the stone without addressing that means the next one forms.

การนัดหมายเพื่อปรึกษา

นพ. สรวีร์ วีระโสภณ รับผู้ป่วยที่ โรงพยาบาลกรุงเทพ สำนักงานใหญ่ และที่โรงพยาบาล สมิติเวช ศรีราชา ในจังหวัดชลบุรี เมื่อวันที่ 088-022-1445. Bring any previous scans, any stone analysis result, and the stone itself if you have kept one — along with a list of your medicines, since several interact with the treatment.

โรงพยาบาลกรุงเทพฯ มีบริการแพทย์ทางไกลสำหรับผู้ป่วยที่ไม่สามารถมาพบแพทย์ด้วยตนเอง รวมถึงผู้ป่วยต่างชาติ กรุณาแจ้งล่วงหน้าทางอีเมลไปยังแผนกศัลยกรรมทางเดินปัสสาวะที่ bhquro@bdms.co.th. Samitivej Sriracha ให้บริการเฉพาะการพบแพทย์ด้วยตนเองเท่านั้น สอบถามเรื่องค่าใช้จ่ายได้ที่โรงพยาบาลโดยตรง ไม่ใช่ผ่านทางเว็บไซต์นี้. An acute attack of stone pain goes to hospital, not to email.

ข้อจำกัดความรับผิดชอบ เนื้อหานี้ถูกเขียนและตรวจสอบโดย นพ. สรวีร์ วีระโสภณ ซึ่งเป็นแพทย์ผู้เชี่ยวชาญที่ได้รับการรับรองจากคณะกรรมการที่ โรงพยาบาลกรุงเทพ สำนักงานใหญ่ และมีวัตถุประสงค์เพื่อการศึกษาเท่านั้น เนื้อหานี้ไม่ใช่คำแนะนำทางการแพทย์ การวินิจฉัย หรือใบสั่งยาสำหรับบุคคลใดทั้งสิ้น และไม่มีการให้คำแนะนำ การวินิจฉัย หรือใบสั่งยาผ่านช่องทางส่งข้อความส่วนตัวหรือสื่อสังคมออนไลน์ นพ. สรวีร์ ไม่มีบัญชีสื่อสังคมออนไลน์สาธารณะใดทั้งสิ้น; บัญชีใดที่เสนอการปรึกษาส่วนตัวในชื่อของเขาเป็นการหลอกลวง ในกรณีฉุกเฉินในประเทศไทย ให้โทร 1669.