Stone composition changes prevention more than any other single piece of information, and it is the piece most often thrown away. Calcium oxalate, calcium phosphate, uric acid, struvite and cystine each carry a different metabolic work-up and a different long-term plan: alkalinisation for uric acid, an infection source hunt for struvite, a genetic and family conversation for cystine, and an entirely different reading of urinary calcium for phosphate against oxalate.
The practical failures are mundane. A fragment retrieved at ureteroscopy goes into a specimen pot nobody labels for analysis; a stone passed at home is described over the phone and discarded; a first presenter is discharged with advice to drink more water and no plan to find out what the stone was made of. Each of those turns a recurrent disease into a series of unconnected episodes.
Give every stone patient a strainer and an instruction to keep what passes, and make composition analysis a standing part of the post-procedure pathway rather than something requested for the interesting cases. When analysis is not available, the 24-hour urine and the serum chemistry still carry most of the decision — but ask for them, rather than assuming somebody in the chain has.
- Send every retrieved fragment for composition analysis as a default, not on request.
- Give a urinary strainer and clear instructions to first presenters who are managed conservatively.
- Request a metabolic work-up in recurrent, bilateral, paediatric and single-kidney stone formers.
- Check serum calcium and urate at the first presentation — they are cheap and change the plan.
- Record the composition where the next clinician will actually see it.
Why it matters
Prevention advice given without knowing the stone type is generic, and generic advice is why recurrence rates have not moved.
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