What is the D5W (Dextrose 5% in Water) rate needed to decrease sodium levels from 129 mmol/L to 126 mmol/L due to overcorrection of hyponatremia?

D5W Rate Calculation for Reversing Overcorrection of Hyponatremia

For overcorrection of hyponatremia from 129 to 126 mmol/L, immediately discontinue current fluids and administer D5W (5% dextrose in water) to relower the sodium level, targeting a correction rate that brings the total 24-hour change to no more than 8 mmol/L from the starting point. 1

Immediate Management Steps

• Stop all hypertonic or isotonic saline infusions immediately to prevent further sodium increase 1
• Switch to D5W as the primary intravenous fluid to provide free water without sodium, allowing dilution of serum sodium 1, 2
• Consider administering desmopressin (2-4 mcg IV or SC) to induce water retention and slow or reverse the rapid sodium rise 1, 3

Calculating the Required D5W Rate

The goal is to decrease sodium by 3 mmol/L (from 129 back to 126 mmol/L) to stay within safe correction limits:

• Use the sodium deficit formula in reverse: Desired decrease in Na (mEq/L) × (0.5 × ideal body weight in kg) = free water deficit 1
• For a 70 kg patient: 3 mEq/L × (0.5 × 70 kg) = 105 mEq or approximately 3 liters of free water needed 1
• Typical D5W infusion rates range from 100-250 mL/hour depending on the urgency and patient's volume status 2
• For gradual correction over 12-24 hours: infuse D5W at 125-150 mL/hour 2

Critical Monitoring Requirements

• Check serum sodium every 2 hours initially during active relowering to ensure the rate of decrease does not exceed 1 mmol/L/hour 1, 3
• Monitor urine output closely as spontaneous water diuresis can complicate management 3
• Adjust D5W rate based on sodium response: if sodium decreases too rapidly, slow the infusion; if inadequate response, increase rate 2
• Target a final 24-hour correction of ≤8 mmol/L from the original baseline to prevent osmotic demyelination syndrome 1, 4

High-Risk Patient Considerations

• Patients with advanced liver disease, alcoholism, malnutrition, or prior encephalopathy require even more cautious management with a maximum total correction of 4-6 mmol/L per day 1
• In these high-risk patients, the overcorrection from baseline may already exceed safe limits, making aggressive relowering with D5W even more critical 1
• Consider ICU-level monitoring for patients requiring active relowering of sodium levels 1

Special Considerations for CRRT Patients

• If the patient is on continuous renal replacement therapy (CRRT), D5W can be infused prefilter (pre-blood pump) at a calculated rate to prevent further overcorrection while maintaining adequate effluent volume 2
• The D5W rate depends on the prescribed CRRT effluent volume and can be calculated to achieve the desired sodium correction rate 2
• This approach allows delivery of recommended effluent volumes (20-25 mL/kg/hr) while controlling sodium correction 2

Common Pitfalls to Avoid

• Failing to act quickly when overcorrection is identified increases the risk of osmotic demyelination syndrome 1, 4
• Inadequate monitoring during relowering can lead to undercorrection or rebound overcorrection 1, 4
• Not considering desmopressin administration when a spontaneous water diuresis complicates management 3
• Using hypotonic saline instead of D5W, which provides less free water per liter and may be insufficient for rapid relowering 2