Calculate infusion rates for symptomatic hyponatremia using the Adrogue-Madias formula.
Adult Male (0.6)
Adult Female / Elderly Male (0.5)
Elderly Female (0.45)
Children (0.6)
Recommended 3% Saline Rate:
0mL/hour
Total Body Water (TBW):0 L
Na+ Change per 1L of 3% Saline:0 mEq/L
Warning: Do not exceed 8-10 mEq/L increase in 24 hours to avoid Osmotic Demyelination Syndrome (ODS).
Understanding Hypertonic Saline Calculations
Hypertonic saline (3% NaCl) is a high-alert medication primarily used in the management of severe, symptomatic hyponatremia or acute cerebral edema. The goal of therapy in hyponatremia is to alleviate neurological symptoms while avoiding the over-correction of sodium levels.
The Adrogue-Madias Formula
This calculator utilizes the Adrogue-Madias formula to predict the effect of 1 liter of 3% hypertonic saline on the patient's serum sodium level:
Change in Serum Na+ = (Infusate Na+ – Serum Na+) / (Total Body Water + 1)
For 3% saline, the Infusate Na+ is 513 mEq/L. Total Body Water (TBW) is estimated based on the patient's weight and demographic factor (0.45 to 0.6).
Important Clinical Considerations
Infusion Targets: In severe cases (seizures, coma), an initial increase of 4-6 mEq/L over the first few hours is often recommended, followed by a slower rate.
Correction Limits: To prevent Osmotic Demyelination Syndrome (ODS), the total correction should generally not exceed 8-10 mEq/L in any 24-hour period.
Monitoring: Serum sodium levels must be checked frequently (every 1-2 hours) during active infusion to adjust the rate.
Practical Example
For a 70kg adult male with a serum sodium of 110 mEq/L, and a target increase of 0.5 mEq/L per hour:
TBW: 70 kg × 0.6 = 42 Liters.
Na Change per 1L: (513 – 110) / (42 + 1) = 9.37 mEq/L.