- Enter the values from a completed, representative 24-hour urine stone-risk collection obtained on the patient's usual ambient diet, with collection completeness verified by creatinine adequacy.
- Select sex (several cutoffs — calcium and uric acid — are sex-specific) and, optionally, enter body weight to apply the 4 mg/kg/day hypercalciuria threshold.
- Fill in each analyte — volume, calcium, oxalate, citrate, uric acid, sodium, pH. Blank fields are skipped, not scored.
- Optionally choose the known stone composition to tailor the advice.
- The result shows an overall risk band and the count of abnormalities, an analyte-by-analyte table with Normal / High / Low badges, and a targeted prevention plan.
All computation runs in your browser; no values are stored or transmitted. This is a transparent analyte-target interpreter — it does not compute proprietary ion-activity supersaturation (EQUIL2 / Litholink SS).
When to Use
Use this interpreter to read a 24-hour urine metabolic stone-risk panel — the standard workup for stone recurrence — and surface the lithogenic abnormalities that drive recurrent calcium oxalate, calcium phosphate, uric acid, and other stones. It maps each analyte to a validated reference target (after Pak's risk-factor framework), flags the direction of any abnormality, and synthesizes an overall risk picture you can use for recurrence counseling and to target therapy.
Appropriate population
Recurrent or high-risk stone formers (first-stone formers who are high-risk — e.g. bilateral disease, nephrocalcinosis, solitary kidney, CKD, or a family history) undergoing a 24-hour urine metabolic evaluation. Best interpreted on a representative ambient-diet collection with completeness confirmed by 24-h creatinine (≈15–20 mg/kg/day in men, 10–15 in women). Two collections are preferred over one.
When NOT to rely on it
Do not over-read an incomplete collection — low creatinine relative to body weight means analytes are spuriously low and the panel is uninterpretable. This is an educational interpreter of analyte targets, not a proprietary supersaturation calculation: it does not solve the EQUIL2 / Litholink iterative ion-activity product. Reference targets vary slightly by laboratory — read the values against your own lab's ranges, and interpret in the full clinical context.
Pearls & Pitfalls
Volume is the most common — and most correctable — risk
Low 24-h urine volume is the single most prevalent and most easily corrected lithogenic factor. Targeting urine output above 2.5 L/day dilutes every stone-forming solute at once and reduces recurrence across all stone types. It is the first intervention for nearly every stone former.
Citrate is protective — LOW is the abnormality
Unlike the other analytes, citrate is an inhibitor: a low value (hypocitraturia, <320 mg/day) is the risk factor. It complexes calcium and inhibits crystal growth. Hypocitraturia frequently coexists with low urine pH (uric-acid risk) or, when paired with high pH and calcium-phosphate stones, points toward distal renal tubular acidosis.
Pitfalls
(1) Sodium drives calcium: do not normalize calcium intake without also restricting sodium, since a high sodium load raises urine calcium. (2) Do not severely restrict dietary calcium — low calcium intake increases oxalate absorption and stone risk; target 1000–1200 mg/day. (3) Read pH in context — persistently high pH (>6.5–7) with hypocitraturia and calcium-phosphate stones suggests RTA; high pH with a low specific gravity and infection suggests struvite. (4) An incomplete collection invalidates the whole panel.
Why Use It
A 24-hour urine panel only changes outcomes if its abnormalities are recognized and translated into targeted therapy. This tool makes the analyte-by-analyte interpretation explicit — which factors are abnormal, in which direction, and how they aggregate into overall risk — so prevention can be matched to the patient's specific physiology rather than applied generically. Identifying hypocitraturia points to potassium citrate; hyperuricosuric calcium oxalate to allopurinol; a persistently acidic urine to alkalinization; and low volume (almost universal) to fluid. Because it is transparent rather than a black-box supersaturation index, every recommendation is traceable to the value that produced it.
24-Hour Urine Stone-Risk Profile Interpreter
Enter the analytes from a completed 24-hour urine stone-risk collection. Each value is scored against its validated reference target; the tool flags the abnormalities, aggregates an overall risk band, and tailors prevention to the abnormalities and the stone composition. Leave any unavailable analyte blank — blanks are skipped.
| Analyte | Value | Target | Result |
|---|
⚕ Transparent analyte-target interpreter — each 24-h analyte is flagged against validated reference targets (volume ≥2.5 L; Ca ≤250 women / ≤300 men or ≤4 mg/kg; oxalate ≤45 mg; citrate ≥320 mg; uric acid ≤800 men / ≤750 women; sodium ≤150 mmol; pH 5.5–6.5) and aggregated into an overall risk band, after Pak's risk-factor framework. It does not compute proprietary ion-activity supersaturation (EQUIL2 / Litholink SS). Requires a complete, representative collection and physician interpretation. Source: Pak CYC. Nephron Clin Pract. 2004; Worcester EM, Coe FL. N Engl J Med. 2010;363:954–963.
Next Steps
Use the profile to drive targeted, physiology-matched prevention.
- Fluid first: for nearly every patient, increase intake to achieve urine output >2.5 L/day — the universal, most correctable risk.
- Diet: restrict sodium (lowers urine calcium), keep dietary calcium normal (1000–1200 mg/day; do not severely restrict), and limit oxalate-rich foods only when hyperoxaluric.
- Pharmacotherapy by abnormality: potassium citrate for hypocitraturia, uric-acid, and calcium stones; allopurinol for hyperuricosuric calcium oxalate; a thiazide for refractory hypercalciuria; urine alkalinization (target pH 6.5–7) for uric-acid stones.
- Evaluate further when high pH coexists with hypocitraturia and calcium-phosphate stones (assess for distal RTA), and confirm collection completeness before acting on a discordant panel.
- Repeat the 24-h urine after a few months on therapy to confirm the targeted abnormality has corrected.
Evidence & References
Reference Targets (24-h Urine)
| Analyte | Target | Abnormality |
|---|---|---|
| Volume | ≥ 2.5 L/day | Low volume (commonest risk) |
| Calcium | ≤ 250 mg (women) / ≤ 300 mg (men); ≤ 4 mg/kg/day | Hypercalciuria |
| Oxalate | < 45 mg/day (≥40 borderline) | Hyperoxaluria |
| Citrate | ≥ 320 mg/day | Hypocitraturia (LOW is the risk) |
| Uric acid | ≤ 800 mg (men) / ≤ 750 mg (women) | Hyperuricosuria |
| Sodium | ≤ 150 mmol/day (>200 clearly high) | High sodium (raises urine Ca) |
| pH | 5.5 – 6.5 | Low → uric acid; high → Ca-phosphate / RTA / struvite |
Risk-band aggregation
| Risk band | Definition |
|---|---|
| Low | 0 abnormalities — analytes within target |
| Moderate | 1–2 abnormalities, none severe |
| High | ≥ 3 abnormalities, or any severe abnormality (e.g. volume <1 L, oxalate >75 mg, citrate <100 mg) |
These targets are validated analyte references; individual laboratories report slightly different ranges. This interpreter flags analytes against targets — it is not a proprietary ion-activity supersaturation (EQUIL2 / Litholink SS) computation.
Evidence & References
The analyte targets and the risk-factor approach derive from Pak's metabolic framework for stone evaluation; Worcester & Coe summarize the physiology of calcium stones and the role of volume, calcium, oxalate, citrate, and sodium; the AUA guideline endorses 24-h urine evaluation and targeted therapy (potassium citrate, thiazides, allopurinol) for recurrent stone formers.
- Pak CYC. Medical management of urinary stone disease. Nephron Clin Pract. 2004;98(2):c49–c53.
- Worcester EM, Coe FL. Calcium Kidney Stones. N Engl J Med. 2010;363(10):954–963.
- Pearle MS, Goldfarb DS, Assimos DG, et al. Medical Management of Kidney Stones: AUA Guideline. J Urol. 2014;192(2):316–324.
