Adult Male (0.6)
Adult Female (0.5)
Elderly Male (0.5)
Elderly Female (0.45)
Children (0.6)
3% Hypertonic Saline (513 mEq/L)
0.9% Normal Saline (154 mEq/L)
0.45% Half Normal Saline (77 mEq/L)
Lactated Ringer's (130 mEq/L)
5% Dextrose in Water (0 mEq/L)
Calculation Summary
CRITICAL SAFETY NOTE: Rapid correction of chronic hyponatremia (>10-12 mEq/L in 24h) carries a high risk of Osmotic Demyelination Syndrome (ODS). A target of 4-6 mEq/L per 24 hours is often safer for high-risk patients.
Understanding Hyponatremia Correction
Hyponatremia is defined as a serum sodium concentration of less than 135 mEq/L. It is one of the most common electrolyte disturbances in clinical practice. The management of hyponatremia requires a delicate balance: correcting sodium levels fast enough to prevent cerebral edema while slow enough to avoid Osmotic Demyelination Syndrome (ODS).
The Adrogue-Madias Formula
This calculator uses the Adrogue-Madias formula to estimate the effect of 1 liter of a chosen IV fluid on the patient's serum sodium level. The formula is expressed as:
Change in Serum Na = (Infusate Na – Serum Na) / (Total Body Water + 1)
Total Body Water (TBW) is calculated as a fraction of body weight based on the patient's age and sex:
Non-elderly Men: 0.6 x weight (kg)
Non-elderly Women: 0.5 x weight (kg)
Elderly Men: 0.5 x weight (kg)
Elderly Women: 0.45 x weight (kg)
Common Infusate Sodium Concentrations
Fluid Type
Sodium Content (mEq/L)
3% Hypertonic Saline
513
0.9% Normal Saline
154
Lactated Ringer's
130
0.45% Normal Saline
77
D5W (Dextrose 5%)
0
Clinical Practice Pearls
When using this hyponatremia correction rate calculator, remember that formulas provide only an estimate. Actual patient response varies significantly due to ongoing fluid losses, renal function, and underlying causes (like SIADH). Frequent monitoring of serum sodium (every 2-4 hours) is essential during the active correction phase.
Correction Speed Recommendations:
Acute Hyponatremia (<48h): Can be corrected more rapidly to prevent brain herniation.
Chronic Hyponatremia (>48h): Limit correction to 6-8 mEq/L in any 24-hour period.
Severe Symptoms: Small boluses of 3% saline (100ml) may be indicated to raise sodium by 2-3 mEq/L quickly.
function calculateCorrection() {
var sNa = parseFloat(document.getElementById("serumNa").value);
var weight = parseFloat(document.getElementById("weight").value);
var tbwFactor = parseFloat(document.getElementById("patientType").value);
var iNa = parseFloat(document.getElementById("infusateNa").value);
var targetHourChange = parseFloat(document.getElementById("targetChange").value);
if (isNaN(sNa) || isNaN(weight) || isNaN(targetHourChange)) {
alert("Please enter all required fields with valid numbers.");
return;
}
// Calculation logic
var tbw = weight * tbwFactor;
// Formula: Change in Serum Na = (Infusate Na – Serum Na) / (TBW + 1)
var changePerLiter = (iNa – sNa) / (tbw + 1);
// Infusion rate (ml/hr) to achieve targetChange (mEq/L/hr)
// Rate = (Target change / Change per liter) * 1000 ml
var infusionRate = (targetHourChange / changePerLiter) * 1000;
var resultDiv = document.getElementById("hypo-result");
var resultText = document.getElementById("result-text");
resultDiv.style.display = "block";
var html = "Estimated Total Body Water (TBW): " + tbw.toFixed(1) + " Liters";
html += "Predicted change in Serum Na per 1 Liter of fluid: " + changePerLiter.toFixed(2) + " mEq/L";
if (infusionRate > 0) {
html += "Required Infusion Rate:" + infusionRate.toFixed(1) + " ml/hr";
html += "To achieve a correction rate of " + targetHourChange + " mEq/L/hr.";
} else {
html += "Note: The chosen infusate has lower sodium than the serum, which will further decrease serum sodium.";
}
resultText.innerHTML = html;
// Smooth scroll to result
resultDiv.scrollIntoView({ behavior: 'smooth', block: 'nearest' });
}