Kidney Stone Risk Calculator
The Kidney Stone Risk Calculator estimates your likelihood of forming kidney stones using 24-hour urine chemistry values. This tool helps clinicians and patients assess stone recurrence risk by analyzing supersaturation levels and urine acidity. Whether you're managing a first-time stone event or monitoring chronic nephrolithiasis, this calculator provides essential data for prevention planning.
How Stone Risk Is Calculated
Kidney stone risk is primarily determined by the concentration of stone-forming substances in your urine relative to inhibitors that prevent crystal formation. This calculator uses established clinical ratios to estimate saturation levels.
CaOx SI = (Calcium × Oxalate) / (Volume × Citrate)
Where:
- Calcium and Oxalate are stone-forming substances.
- Volume and Citrate act as diluents and inhibitors, respectively.
The Calcium Oxalate Supersaturation Index (CaOx SI) measures how likely calcium oxalate crystals are to form. Higher levels of calcium or oxalate, or lower levels of urine volume and citrate, increase this index. Similarly, the Uric Acid Risk Index accounts for concentration and pH, as acidic urine promotes uric acid stone formation.
These simplified models provide a reference snapshot of your chemical risk factors without requiring complex laboratory software.
What Your Stone Risk Category Means
Understanding your risk category is the first step toward preventing recurrence. Your Calculation classify you into Low, Moderate, or Higher statistical association based on how saturated your urine is with crystals.
For Lower statistical association:
Your urine chemistry suggests a low likelihood of stone formation. Maintain your current fluid intake and dietary habits to keep volume high and mineral concentrations in check.
For Moderate Risk:
You are approaching the threshold where crystals may form. Increasing your fluid intake to achieve at least 2.5 L of urine per day is often the most effective intervention to lower saturation indices.
For Higher statistical association:
Your urine is highly saturated, indicating a significant chance of stone growth or recurrence. Dietary modifications—such as reducing sodium and animal protein—and potential medications prescribed by a urologist are often necessary to reduce risk.
Calculation logic verified using publicly available standards.
View our Accuracy & Reliability Framework →