腎結石に対するクエン酸カリウム：その効果と限界

最終更新日： 2026年8月30日

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One of the questions I am asked most often in the stone clinic is whether potassium citrate can treat a kidney stone, or prevent another one after successful stone surgery. The honest answer is this: most kidney stones cannot be dissolved or removed by medication alone — citrate’s main role is in reducing the recurrence rate. There is one important exception, and this article explains both.

The two protective effects of クエン酸カリウム

1. It alkalinizes the urine. The uric acid stone is the only type that thrives in acidic urine, so holding the urine pH at 6.5–7.0 with citrate therapy can genuinely dissolve it. Thai data show that around 20.9% of stone patients have uric acid stones — roughly 1 in 5 — and it is this group that may be treated with oral citrate alone.
2. It inhibits calcium stone formation. Calcium stones account for up to 80% of all kidney stones. Citrate binds calcium ions in the urine and prevents them crystallising. A large systematic review in 2015 confirmed that citrate therapy significantly limits stone growth and reduces the recurrence rate — but note that this is prevention, not dissolution.

Note the upper end of that pH range. The target is a window rather than a direction of travel: pushing the urine too alkaline creates favourable conditions for a different kind of stone to form instead. That is the practical reason the pH is monitored rather than simply pushed up, and the reason a dose is adjusted rather than increased until symptoms settle.

The part of the name that matters: potassium

Everything above is about the citrate. The potassium is the half that determines whether this medicine is safe for you, and it is the reason it is a prescription decision rather than a shopping one.

Potassium citrate raises the potassium level in the blood. In a person with normal kidneys and no interacting medication, the kidneys simply excrete the excess and nothing happens. But if the kidneys are not working well, or if you take a medicine that already holds potassium in, the level can climb — and a high blood potassium disturbs the heart’s rhythm. It is one of the few side effects in urology that can be dangerous before it is uncomfortable.

Tell your doctor before starting citrate therapy if any of these apply to you:

• Reduced kidney function of any degree, or a kidney transplant. This matters especially in stone formers, some of whom have quietly lost kidney function over the years.
• Blood pressure or heart medication — several of the common classes raise potassium in their own right, and the combination is where problems occur. Bring the actual boxes or a photograph of them rather than trying to remember names.
• Water tablets, since some lower potassium and others raise it, and the difference is not obvious from the outside.
• Regular anti-inflammatory painkillers, potassium supplements, or salt substitutes — the low-sodium salts sold as a healthier alternative are usually potassium-based, which people rarely think to mention.
• A stomach ulcer, or difficulty swallowing tablets, since the tablet forms can irritate the gut lining.

None of these necessarily rule the treatment out. What they do is change whether a blood test is needed first, how the dose is set, and how often things are checked. A blood test for potassium and kidney function before starting, and again once you are established on it, is a normal part of doing this properly — if nobody has mentioned one, it is a reasonable thing to ask about.

Stop the medication and be seen the same day — in Thailand you can call 1669 — if you develop: muscle weakness, a feeling of heaviness in the limbs, tingling or numbness, palpitations or an irregular heartbeat, unusual confusion, or feeling faint. These can be signs of a high potassium level. The same applies to severe abdominal pain, persistent vomiting, or black or bloody stools, which suggest the medication has irritated the gut rather than simply upset it.

The drawbacks

• Gastrointestinal side effects — stomach upset, nausea, bloating and diarrhoea are common. Taking it with meals and plenty of water helps.
• It demands compliance — optimal therapy means three doses a day, every day, alongside regular self-monitoring of urine pH. This is where most patients struggle.
• No guarantee — stone formation is multifactorial, so citrate reduces the odds of recurrence rather than removing them.

Whether citrate therapy is worth it depends on your stone type — ideally confirmed by stone analysis — your urine studies and your stone history, so it is a decision to make with your urologist rather than at the pharmacy counter. For stones that need removing rather than preventing, see how shockwave lithotripsy (ESWL) works. For the wider question of why stones form at all and what else can be done about it, see 腎臓結石ができる理由.

お客様からよくいただくご質問

Q1: クエン酸カリウムは腎臓結石を溶かすことができますか？

クエン酸カリウムが腎結石を溶解できるのは、特定の状況、すなわち尿酸結石の場合に限られます。クエン酸療法は尿をpH 6.5～7.0のアルカリ性にすることで、時間の経過とともに尿酸結晶が溶解する環境を作り出します。腎結石の最大80％を占めるより一般的なカルシウム含有結石については、クエン酸療法は新たな結石の形成を防ぐのに役立ちますが、既存の結石を溶解することはできません。.

Q2: クエン酸カリウムはどのようにして腎臓結石を防ぐのですか？

クエン酸カリウムは2つの方法で作用します。第一に、尿をアルカリ化することで、尿酸結石を標的とし、溶解を助けます。第二に、クエン酸塩は尿中のカルシウムイオンに結合し、結石化を防ぐことで、カルシウム結石の形成を自然に阻害します。2015年の大規模な系統的レビューでは、クエン酸塩療法が結石の再発率を大幅に低下させることが確認されました。.

Q3: Is potassium citrate safe for everyone?

No, and this is the part most often overlooked. Potassium citrate raises the potassium level in the blood. With normal kidneys and no interacting medication the excess is simply excreted, but where kidney function is reduced, or where another medicine already holds potassium in, the level can climb — and a high blood potassium disturbs the heart’s rhythm. Tell your doctor about any reduced kidney function or kidney transplant, blood pressure and heart medications, water tablets, regular anti-inflammatory painkillers, potassium supplements, and low-sodium salt substitutes, which are usually potassium-based and rarely mentioned. A stomach ulcer or difficulty swallowing tablets also matters. None of these necessarily rule the treatment out; they change whether a blood test is needed first, how the dose is set and how often it is checked.

Q4: Do I need blood tests while taking potassium citrate?

Yes. A blood test for potassium and kidney function before starting, and again once you are established on treatment, is a normal part of prescribing this properly. If nobody has mentioned one, it is a reasonable thing to ask about. Urine pH is monitored separately, and the target is a window of 6.5-7.0 rather than a direction of travel, because pushing the urine too alkaline encourages a different kind of stone to form instead.

Q5: Who should take potassium citrate for kidney stones?

Potassium citrate is most beneficial for patients with uric acid kidney stones, those with low urinary citrate levels (hypocitraturia), and patients with calcium oxalate stones who have had prior stone surgery and want to reduce recurrence risk. Your urologist can determine whether citrate therapy is appropriate based on your stone type (ideally confirmed by stone analysis), urine studies, kidney function, current medications, and overall stone history.

Q6: What are the side effects of potassium citrate therapy?

The common ones are gastrointestinal: stomach upset, nausea, bloating, and diarrhea. These are usually related to the dosing schedule, as optimal therapy requires taking the medication three times daily, and taking citrate with meals and adequate water can help. If side effects are severe, your doctor can adjust the formulation or dosage. The important but less common problem is a rise in blood potassium, which is why kidney function and interacting medications are checked before starting.

Q7: Which symptoms mean I should stop and seek urgent help?

Stop the medication and be seen the same day — in Thailand you can call 1669 — for muscle weakness, a feeling of heaviness in the limbs, tingling or numbness, palpitations or an irregular heartbeat, unusual confusion, or feeling faint. These can indicate a high potassium level, which is one of the few side effects in this field that can be dangerous before it is uncomfortable. Severe abdominal pain, persistent vomiting, or black or bloody stools also need same-day assessment, as they suggest the medication has irritated the gut lining rather than simply upset the stomach.

Q8: Can I buy potassium citrate over the counter for kidney stones?

While some citrate-containing supplements are available over the counter, self-medicating without medical guidance is not recommended, and the reason is not only that it may not work. Effective citrate therapy requires knowing your stone type (confirmed by stone analysis), monitoring urine pH regularly, and maintaining appropriate dosing — but it also requires knowing that your kidney function and current medications make the potassium safe for you, which cannot be established at a pharmacy counter. Kidney stone formation is multifactorial and requires a comprehensive evaluation by a urologist to design the most effective prevention strategy for your individual situation.

Q9: Can I discuss citrate therapy by video consultation?

Yes, and it suits this well, since the decision rests on your stone analysis, previous urine and blood results and your current medication list rather than on an examination. Bangkok Hospital Headquarters offers a Telemedicine service, arranged in advance by email to the Urology department at bhquro@bdms.co.th — send any stone analysis, kidney function results and a photograph of all the medicines you take, including supplements and salt substitutes. Blood tests are arranged in person. Samitivej Sriracha is in-person only, booked through the Urology department line 088-022-1445.

腎臓結石があり、クエン酸カリウム療法がご自身に適しているかどうかのガイダンスをご希望の場合は、ソアラウィー・ウィーラソポーン医師がバンコク・ホスピタル・ヘッドクォーターズで専門的な診察を行っております。. 診療をご予約. サミティウェート・シーラチャ病院のご予約は、泌尿器科（電話番号：）までお問い合わせください。 088-022-1445. Questions about the cost of consultation, testing or medication should go to the hospital directly — for Bangkok Hospital, by email to bhquro@bdms.co.th.

参考文献

• Citrate salts for preventing and treating calcium containing kidney stones: systematic review. PubMed 26439475

免責事項 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. Potassium citrate is a potassium salt and is not suitable for everyone; kidney function and current medications must be assessed before it is started, and it should not be self-prescribed. 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.