Renal & Electrolytes

Sodium Change per Liter of Infusate (Adrogué-Madias) Calculator

Expected change in serum sodium from 1 liter of an IV fluid, from its sodium and potassium and the total body water.

Reviewed by Alex G, BSN, RN, CEN, CCRN, CMC, NREMT-P · From the Reference tab of the app

Turn on JavaScript to use this calculator, or open it in the web app.

Formula

Change in serum Na per liter = (infusate Na + infusate K − serum Na) ÷ (total body water + 1)
Total body water (L) = weight (kg) × 0.6 in children; 0.6 in men and 0.5 in women under 65; 0.5 in men and 0.45 in women 65 or older
Infusates, Na (K) in mEq/L: 5% dextrose 0; 0.2% NaCl 34; 0.45% NaCl 77; lactated Ringer’s 130 (4); Plasma-Lyte A 140 (5); 0.9% NaCl 154; 3% NaCl 513; 5% NaCl 855

How it is used

• Hyponatremia, US expert panel: limit the rise to 10–12 mEq/L in any 24 hours and 18 in any 48 hours, or 8 in any 24 hours at high risk of osmotic demyelination (sodium 105 or less, hypokalemia, alcohol use disorder, malnutrition, advanced liver disease); aim for at least 4–8 (4–6 at high risk) (Verbalis 2013).
• Hyponatremia, European guideline: limit the rise to 10 mEq/L in the first 24 hours and 8 mEq/L in each 24 hours after that until sodium reaches 130 (Spasovski 2014).
• The formula treats the patient as a closed system: urine and other ongoing losses are ignored, and a water diuresis once ADH falls can raise sodium much faster than predicted (Adrogué & Madias 2000).
• Hypernatremia: lower sodium by about 10 mEq/L a day when it is chronic or of unknown duration; about 1 mEq/L an hour is appropriate only when it developed over hours (Adrogué & Madias 2000).

Key points

• If sodium rises faster than the limit, tell the provider at once: re-lowering with electrolyte-free water and desmopressin is recommended for overcorrection (Spasovski 2014).

Same formula as the app. Open it in the web app.

Related one-pagers

• Electrolyte ImbalancesOvercorrection usually comes from the patient: once the ADH stimulus ends (volume restored, thiazide stopped, cortisol given, nausea relieved), dilute urine pours out. With Na under 120, the rise beat the Adrogué–Madias formula (next section) in 74% of patients, by 2.4 times on average (Europe 2014). Rising urine output with falling specific gravity means check Na now.
• ABG Interpretation in 6 Steps
• CRRT (Continuous Renal Replacement)

Related calculators

• Anion Gap
• BUN/Cr Ratio
• Corrected Calcium
• Corrected Sodium (Hyperglycemia)
• Creatinine Clearance (Cockcroft-Gault)
• CRRT Effluent Dose (mL/kg/h)
• Fractional Excretion of Sodium (FENa)
• Fractional Excretion of Urea (FEUrea)

For education and exam preparation only. Follow your institution’s protocols. For education and exam preparation only. Verify results independently and follow your institution’s protocols. Not a substitute for clinical judgment.