Der stille Architekt der Steine: Nierensteinerkrankung durch Harnsäure meistern

Zuletzt aktualisiert: August 16, 2026

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It is a privilege to share this reflection. Looking back at the 27th Annual Scientific Meeting of the Cambodian Society of Surgery, where I represented the Urology Department of Royal Phnom Penh Hospital on 25 November 2022, I am struck by professional gratitude. It was my third presentation at that meeting, and a grounding reminder of why we do this work: the patient.

Today I want to move beyond the data of clinical trials and narrate a real-world journey — a case that illustrates almost every challenge uric acid kidney stones can pose. If you have been told you have uric acid stones, or you simply want to understand why some kidney stones come back so aggressively, this article is for you.

First: When a Stone Is an Emergency

Most of this article is about long-term management, which is slow and undramatic work. Before that, the part that is neither. Go to an emergency department, do not wait for an appointment, if you have:

• Fever or shaking chills together with flank pain — a blocked kidney that is also infected can progress to sepsis within hours, and it needs drainage rather than antibiotics alone. This is the single most dangerous situation in stone disease.
• Pain severe enough that ordinary painkillers are not touching it, or persistent vomiting.
• Passing little or no urine, particularly if you have only one working kidney or stones on both sides.
• Flank pain in pregnancy, or in anyone with known kidney impairment or a transplanted kidney.

What Makes Uric Acid Stones Different?

Uric acid stones behave differently from the more common calcium oxalate type in three ways:

• They are pH-dependent. Uric acid crystals form when the urine becomes too acidic — typically a urine pH below 5.8.
• They can be dissolved. Unlike calcium-based stones, uric acid stones can often be dissolved with medication — alkalinisation therapy, or chemolitholysis. This is close to unique among stone types.
• They recur readily. Without ongoing management they come back, often quickly.

For the fundamentals of how stones form and how diet affects them, see my earlier guide to kidney stone prevention and management, and the wider kidney stone service.

A Patient Story — From Agony to Recovery

The account that follows is drawn from cases I managed during my years in urology. Identifying details have been changed or combined, and it is presented for what it teaches rather than as a record of any one person. Medication names and doses are described in general terms; treatment must always be individualised.

The Sudden Storm

A man in his fifties, previously healthy with no chronic illness — the kind of patient who rarely thinks about hospitals until he has no choice. That choice was made for him by sudden, agonising right flank pain.

CT imaging showed the extent of it: a 6.5 mm stone lodged at the right ureterovesical junction, obstructing the kidney, with two further stones (14 mm and 4 mm) in the lower pole of the same kidney.

The immediate priority was relieving the obstruction and the pain. We performed endoscopic holmium laser lithotripsy on the obstructing stone and placed a double-J ureteric stent so the kidney could drain, followed by two sessions of extracorporeal shock wave lithotripsy for the stones remaining in the kidney.

When Healing Goes Wrong

Six weeks later he returned to have the stent removed — normally routine. The flexible cystoscopy failed, for a reason that is a urologist’s nightmare: severe stent encrustation. In six weeks his body had coated the stent in stone material.

We returned to theatre to remove the encrusted stent, and crucially we kept those fragments and sent them for analysis. That single decision changed everything.

The Diagnosis, and a False Peace

The analysis came back: uric acid. That was the moment the case turned. We started alkalinisation therapy with potassium citrate on a structured daily regimen. Within weeks things looked excellent — urine pH around 7.0, and imaging showing only tiny residual fragments. The patient felt fine.

Feeling fine was the trap.

The Relapse — One Year Away

Believing himself cured, he stopped the medication and stopped attending follow-up. He was out of our care for a year. He returned in distress with blood in his urine, and the new CT was startling: a 4 cm staghorn stone filling the right renal collecting system, multiple smaller stones alongside it, and — in a kidney that had previously been clear — stones up to 10 mm on the left.

He was frustrated and confused. Why so fast? The answer is what makes these stones so unforgiving: once the urine turns acidic again, uric acid crystallises rapidly. Months without alkalinisation can undo years of progress.

The Intensive Phase — and a Lesson in Overcorrection

We restarted alkalinisation immediately. A month later nothing had changed, and a new stone had appeared on the left. The laboratory data explained why: his urine pH was 5.0 — still far too acidic for anything to dissolve — and his serum uric acid was well above the normal range.

We moved to a multi-pronged approach: a higher citrate dose with daily home monitoring of urine pH, allopurinol to reduce uric acid production at source, and a target urine pH of 6.5 to 7.2.

Then we hit a snag in the opposite direction. His urine pH climbed to 8.0 and his creatinine rose. Too much alkalinity carries its own problems — it can promote calcium phosphate stones and stress the kidneys. We pivoted again, stopping the citrate combination and switching to a lower, more controlled dose of oral sodium bicarbonate.

That episode is the most instructive part of the whole case, and it is why this is a supervised treatment rather than a self-managed one. Alkalinisation is not a case of more is better — there is a window, and both edges of it cause harm.

Success Through Patience

Eventually we reached the goal. Imaging showed dramatic improvement, urine pH stabilised around 7.0, and kidney function recovered. Dissolving stones with medicine rather than removing them surgically had finally worked. He was delighted. So were we — two years after the first episode of pain.

The Science of Uric Acid Stones

Key fact	Clinical significance
Prevalence	Uric acid stones make up roughly a tenth of all kidney stones — less common than calcium oxalate, but more aggressive when they appear.
Recurrence	High risk of returning if not actively managed long term, even after a stone is dissolved or removed.
The pH factor	A urine pH below 5.8 is the primary driver of crystallisation. Keeping pH in the 6.5-7.2 range is the aim; above about 7.5 brings its own problems.
Stone analysis	Recommended for first-time stone formers and anyone with early recurrence — it is the only way to know what type of stone you make.

Why Stone Analysis Is Non-Negotiable

The single most important moment in this journey was the decision to send those tiny encrustation fragments for analysis. Without that result we would have gone on treating him as an ordinary stone former and missed the one therapy that could actually dissolve his stones.

If you have ever passed a stone, ask whether it was sent for composition analysis. If it was not, ask what happens when — not if — the next one appears. Keep any stone you pass, however small; a fragment in a clean container is worth more than a description of it.

What to Do If You Have Had a Uric Acid Stone

• Do not stop the medication when you feel better. That is exactly how the patient above lost two years. There is nothing to feel when the urine turns acidic again, right up until the pain returns.
• Monitor your urine pH with test strips if your doctor has asked you to, aiming for a stable 6.5 to 7.2. Record the numbers; do not adjust your own dose on the strength of them. The overcorrection described above happened under supervision — it happens faster without.
• Hydrate consistently, aiming for a urine output that keeps the urine pale. If you have heart failure or kidney impairment, agree the target with your doctor rather than drinking to a number from an article.
• Address the drivers. High-purine intake (organ meats, anchovies, shellfish), heavy alcohol, obesity and metabolic syndrome all push urine pH downward. This matters as much as the medication.
• Stay in follow-up. Imaging and urine checks every 6 to 12 months catch problems before they become surgical emergencies.

Two Things to Report About the Medication Itself

A rash after starting allopurinol should be reported immediately and the drug stopped until you have been assessed. Allopurinol very occasionally triggers a severe hypersensitivity reaction involving the skin, and a rash with fever, mouth ulcers or blistering is an emergency. This risk is linked to a genetic marker that is more common in several Asian populations, which is why the caution matters here more than a Western textbook might suggest. Testing for it before starting is available in some settings; ask.

Sodium bicarbonate carries a sodium load. That is worth knowing if you have high blood pressure, heart failure or kidney impairment, and it is one reason the choice between citrate and bicarbonate is a medical decision rather than a matter of what is easiest to buy.

Kernaussagen

• Stone analysis is the foundation. It lets us treat the cause rather than the episode.
• Uric acid stones are the one kind you can often dissolve — and the one kind that comes straight back if you stop.
• The target is a window, not a direction. Too alkaline is its own problem, which is why this is monitored rather than self-managed.
• Fever with flank pain is the emergency that everything else on this page is trying to prevent.

Surgery removes a stone; only sustained medical management keeps a patient stone-free. If you have a history of uric acid stones, recurrent stones, or a stone composition nobody has established, Dr. Soarawee Weerasopone consults at Bangkok Hospital Hauptsitz and at Samitivej Sriracha Hospital, Chonburi — 088-022-1445.

Bangkok Hospital Telemedicine is available for patients who cannot attend in person, including international patients — arrange it in advance by email to the Urology department at bhquro@bdms.co.th. It suits reviewing results, pH records and a long-term plan; acute flank pain with fever needs an emergency department rather than a teleconsultation. Samitivej Sriracha is in-person only.

Frequently Asked Questions About Uric Acid Kidney Stones

Can uric acid kidney stones really be dissolved without surgery?

Often, yes. Uric acid stones are close to unique in that they can be dissolved through alkalinisation therapy, which raises urine pH into the 6.5 to 7.2 range — a process called chemolitholysis. It requires close supervision, urine pH monitoring and consistent adherence over months. Calcium-based stones cannot be dissolved this way.

When is a kidney stone an emergency?

Fever or shaking chills with flank pain is the critical one: a blocked kidney that is also infected can progress to sepsis within hours and needs drainage, not antibiotics alone. Also go in for pain that ordinary painkillers do not touch, persistent vomiting, passing little or no urine, or flank pain in pregnancy, in a single kidney, or with known kidney impairment.

What causes uric acid stones to form?

They form when the urine becomes too acidic, typically below pH 5.8. Contributors include high-purine intake (red meat, organ meats, shellfish), heavy alcohol use, obesity, metabolic syndrome, gout and chronic dehydration. Genetic factors and some medications also play a part.

Why do uric acid stones come back so quickly?

Because the underlying problem — acidic urine — returns as soon as alkalinisation stops. Months without medication can be enough for new stones to form, including large staghorn stones filling the kidney. Nothing warns you: there is no symptom attached to acidic urine until a stone announces itself.

What urine pH should I aim for, and can I adjust my own dose?

The target is 6.5 to 7.2. Below 5.8 promotes uric acid crystallisation; above roughly 7.5 can promote calcium phosphate stones and stress the kidneys. Record your readings and bring them to your appointments, but do not change your own dose on the strength of a test strip — overcorrection is a real complication, not a theoretical one.

Are there side effects of the medication to watch for?

Two worth knowing. A rash after starting allopurinol should be reported immediately and the drug stopped until you are assessed — rarely it triggers a severe skin reaction, and rash with fever, mouth ulcers or blistering is an emergency. The genetic marker linked to that risk is more common in several Asian populations. Separately, sodium bicarbonate carries a sodium load that matters in high blood pressure, heart failure or kidney impairment.

Why is stone analysis so important?

It is the only way to know what type of stone you form, which directly determines treatment. A uric acid stone can be dissolved with medication; a calcium oxalate stone cannot. Without analysis, management is guesswork — and patients miss the chance for the least invasive long-term care. Keep any stone you pass, however small.

Haftungsausschluss: 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. Patient details have been changed or combined to protect privacy, and treatment regimens described are illustrative and must be individualised. No advice, diagnosis or prescription is given through personal messaging channels or social media. Fever with flank pain may indicate an infected obstructed kidney — seek emergency care rather than waiting for an appointment. Always consult a qualified healthcare professional before starting or stopping any medical treatment.