Rare kidney & urinary condition
Cystinuria and kidney stones
Cystinuria is an inherited transporter defect that floods the urine with poorly soluble cystine, causing recurrent stones from a young age; high fluid intake, urine alkalinisation and specialist follow-up prevent most of them.
Key points
The essentials at a glance.
What to look out for, how the diagnosis is confirmed, who looks after it, and the options that exist.
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01
Suspect it with stones in childhood or young adulthood, recurrent stones, or a family history; cystine stones are faintly visible on X-ray and have a characteristic appearance.
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02
Diagnosis: stone analysis and 24-hour urine cystine measurement; genetic testing is available.
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03
The cornerstone is dilution: enough fluid, spread across day and night, to keep urine cystine below its solubility.
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04
Alkalinising the urine (potassium citrate) increases cystine solubility; thiol drugs (tiopronin, penicillamine) are added when this fails.
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05
Lifelong metabolic follow-up in a stone clinic dramatically reduces surgeries over a lifetime.
Understanding it
What it is, and what happens next.
In plain English - what is going on, how specialists confirm it, and the routes to treatment in the UK.
Cystine is barely soluble, and in cystinuria the transporter that should reclaim it from the urine is broken - so every day is a race between dilution and crystallisation. Left to its own devices the disease produces stone after stone, and its staircase of procedures can scar kidneys over decades; managed properly, with the unglamorous disciplines of water and urinary chemistry, many patients stay stone-free for years.
Care belongs in a metabolic stone service: baseline 24-hour urine studies personalise the fluid target, potassium citrate titrates urine pH into the protective range, thiol agents are layered in for high excretors with monitoring for side effects, and surveillance imaging catches small stones while they are still treatable by non-invasive means. In many parts of the UK, routine NHS outpatient referrals for problems like this can take several months, whereas an initial appointment with a private consultant is typically available within around two weeks.
A quiet reminder
This guide is for information, not medical advice.
Your GP or specialist knows your history and can tell you which parts apply to you. If in doubt, speak to them.
Published 2026-09-27 · Next review 2027-09-27
Frequently asked
Common questions about Cystinuria and kidney stones.
Quick, plain-English answers to what people ask us most.
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What is cystinuria?
Cystinuria is an inherited transporter defect that causes the kidneys to leak excessive amounts of cystine (an amino acid) into the urine, where it forms poorly soluble crystals leading to recurrent kidney stones.
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What causes cystinuria?
It's caused by inherited mutations affecting the kidney's ability to reabsorb cystine and certain other amino acids from urine, leading to abnormally high cystine concentrations that crystallise into stones.
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What are the symptoms of cystinuria?
The main symptom is recurrent kidney stones, causing severe flank pain, blood in the urine, and sometimes urinary tract infections, typically starting at a younger age than typical calcium-based kidney stones.
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Is cystinuria dangerous?
Repeated stone formation can cause significant pain and, if untreated over time, kidney damage from recurrent obstruction or infection, so ongoing prevention and monitoring matter considerably.
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Is cystinuria hereditary?
Yes, it's inherited, typically in an autosomal recessive pattern, meaning family members may also be affected or carry the gene. Genetic counselling can help clarify risk to relatives.
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Can cystinuria stones be prevented?
Yes, largely through high fluid intake (to dilute urine cystine concentration), urine alkalinisation, and dietary modification, sometimes alongside specific medications for those who continue forming stones despite these measures.
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How are cystinuria stones treated when they form?
Treatment depends on stone size and symptoms - some pass naturally with adequate fluids and pain relief, while larger stones may need procedures such as lithotripsy or surgical removal, similar to other kidney stone types.
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How is cystinuria diagnosed?
Diagnosis typically involves urine testing for cystine levels, stone composition analysis (if a stone is passed or removed), and sometimes genetic testing to confirm the underlying cause.
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Cystinuria vs typical calcium kidney stones - what's the difference?
Cystinuria stones are caused by a specific genetic transporter defect and tend to recur throughout life starting at a younger age, whereas typical calcium stones are more often related to diet, hydration, and other metabolic factors without a single genetic cause.
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When should I see a specialist about recurrent kidney stones?
See a urologist or nephrologist if you have recurrent kidney stones, particularly starting at a young age, as this raises the possibility of cystinuria or another underlying metabolic cause. A private specialist consultation is often available within about two weeks.