💧 Adrogué–Madias Fluid Formula
The Adrogué–Madias formula predicts how each liter of a chosen infusate will change serum sodium, guiding dysnatremia correction.
Limit chronic hyponatremia correction to ≤8–10 mmol/L/24h to avoid osmotic demyelination, and chronic hypernatremia to ≤10–12 mmol/L/24h to avoid cerebral edema (original synthesis · not guideline verbatim).
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When to use
Enter current sodium, weight, sex, age category, and infusate; the tool returns the predicted ΔNa per liter and estimated total body water.
How it works
ΔNa per liter = (infusate Na − serum Na) / (total body water + 1). TBW = weight × factor (0.6 male, 0.5 female; 0.5/0.45 if elderly).
Key points
- Limit chronic hyponatremia correction to ≤8–10 mmol/L/24h to avoid osmotic demyelination, and chronic hypernatremia to ≤10–12 mmol/L/24h to avoid cerebral edema (original synthesis · not guideline verbatim).
- The formula ignores ongoing urinary and insensible losses, so it is a starting estimate that requires frequent re-measurement.
- Hypertonic 3% saline (Na 513) raises sodium fastest; 5% dextrose (Na 0) lowers it and is used for hypernatremia.
References
- Adrogué HJ, Madias NE. Hyponatremia. N Engl J Med. 2000.
- Adrogué HJ, Madias NE. Hypernatremia. N Engl J Med. 2000.
Worked calculation
The values below come from this tool's own example placeholders and are computed server-side with the formula shown on this page, so the arithmetic can be checked quickly. It demonstrates how to substitute values only — it is not clinical advice and not a real case.
| Current serum sodium | 120 mmol/L |
|---|---|
| Weight | 70 kg |
| Sex | Male |
| Elderly | Yes |
| Infusate type | 3% hypertonic saline (Na 513) |
→Predicted ΔNa per liter10.9mmol/L
- Total body water (est.)：35 L
- Direction：Raises serum sodium
| Current serum sodium | 120 mmol/L |
|---|---|
| Weight | 70 kg |
| Sex | Female |
| Elderly | No |
| Infusate type | 5% dextrose (Na 0) |
→Predicted ΔNa per liter-3.3mmol/L
- Total body water (est.)：35 L
- Direction：Lowers serum sodium
Frequently asked questions
- What is Adrogué–Madias Fluid Formula?
- The Adrogué–Madias formula predicts how each liter of a chosen infusate will change serum sodium, guiding dysnatremia correction.
- How is Adrogué–Madias Fluid Formula calculated? What is the core formula?
- ΔNa per liter = (infusate Na − serum Na) / (total body water + 1). TBW = weight × factor (0.6 male, 0.5 female; 0.5/0.45 if elderly).
- When is Adrogué–Madias Fluid Formula used?
- Enter current sodium, weight, sex, age category, and infusate; the tool returns the predicted ΔNa per liter and estimated total body water.
- What are the key clinical points for Adrogué–Madias Fluid Formula?
- Limit chronic hyponatremia correction to ≤8–10 mmol/L/24h to avoid osmotic demyelination, and chronic hypernatremia to ≤10–12 mmol/L/24h to avoid cerebral edema (original synthesis · not guideline verbatim). The formula ignores ongoing urinary and insensible losses, so it is a starting estimate that requires frequent re-measurement. Hypertonic 3% saline (Na 513) raises sodium fastest; 5% dextrose (Na 0) lowers it and is used for hypernatremia.
- What are the limits and cautions when using Adrogué–Madias Fluid Formula?
- For licensed clinicians and clinical researchers. Interpret results with history, investigations and local protocols; not a diagnosis or prescription, and not a substitute for multidisciplinary decision-making or local guidelines.
- How is Adrogué–Madias Fluid Formula calculated in practice? Can you show a worked example?
- Inputs: Current serum sodium 120 mmol/L, Weight 70 kg, Sex Male, Elderly Yes, Infusate type 3% hypertonic saline (Na 513) → Result: Predicted ΔNa per liter 10.9 mmol/L（Total body water (est.): 35 L, Direction: Raises serum sodium） Inputs: Current serum sodium 120 mmol/L, Weight 70 kg, Sex Female, Elderly No, Infusate type 5% dextrose (Na 0) → Result: Predicted ΔNa per liter -3.3 mmol/L（Total body water (est.): 35 L, Direction: Lowers serum sodium）