# Stone Prevention: Start With Composition

Physiological plausibility and older trial data do not make every intervention equally proven. Reassess recurrence, tolerability, and the patient's ability to sustain the plan.

![Infographic: Stone Prevention: Start With Composition](https://urinenephrology.org/visual-reference/images/mastery-stones.png?v=20261003c)

## Supersaturation drives crystallization

Urine volume, solute excretion, inhibitors, and pH determine the tendency of a particular salt to form crystals.

## Identify the stone

Composition can reorganize the differential and treatment plan. Calcium oxalate, calcium phosphate, uric acid, infection, and cystine stones are not interchangeable.

## Use a metabolic collection when it will change care

For recurrent or high-risk stone disease, one or two 24-hour urine collections can measure volume, pH, calcium, oxalate, uric acid, citrate, sodium, potassium, and creatinine. Interpret on the usual diet and assess collection adequacy. Pair the results with stone composition.

## Choose the prevention lever

When appropriate, aim for urine volume of at least 2.5 L/day through individualized fluid intake. High urine sodium may sustain calciuria; low citrate can suggest a citrate strategy. Preserve appropriate dietary calcium with meals rather than automatically restricting it, and address excessive oxalate in a compatible calcium-oxalate pattern.

## Do not alkalinize every stone former

Uric-acid stones and calcium-phosphate stones respond differently to urine pH. Alkali can reduce uric-acid supersaturation yet increase calcium-phosphate risk if pH rises excessively. Recheck urine chemistry and recurrence after a treatment change instead of assuming every higher citrate or pH value is better.

## Keep evidence limitations visible

Physiological plausibility and older trial data do not make every intervention equally proven. Reassess recurrence, tolerability, and the patient's ability to sustain the plan.

## Supporting evidence

- [Supporting guideline or source](https://www.auanet.org/documents/Guidelines/PDF/clinical-guidance/Medical-Management-of-Kidney-Stones.pdf)

## Source lessons

- [metabolic stone workup](https://urinenephrology.org/mastery/stone-disease/metabolic-stone-workup.html)

Read alongside the full lessons; the findings and decisions shown here require the stated clinical context.