How are intravenous (IV) fluids administered to correct hyponatremia in an Addisonian crisis?

IV Fluid Management for Hyponatremia in Addisonian Crisis

In Addisonian crisis with hyponatremia, isotonic (0.9%) saline should be administered initially at a rate of approximately 1 L/hour, followed by a slower infusion rate, while simultaneously administering hydrocortisone 100 mg IV bolus followed by 100-300 mg/day as continuous infusion or divided doses every 6 hours. 1

Initial Management

1. Immediate hydrocortisone administration:

   • Give hydrocortisone 100 mg IV bolus immediately
   • Continue hydrocortisone 100-300 mg/day as continuous infusion or divided doses every 6 hours

2. Initial fluid resuscitation:

   • Begin isotonic (0.9%) saline at approximately 1 L/hour initially
   • This addresses both volume depletion and hyponatremia simultaneously

3. Monitoring parameters:

   • Check serum sodium every 2 hours for severe hyponatremia (Na <125 mEq/L)
   • Check serum sodium every 4 hours for mild hyponatremia
   • Monitor urine output and specific gravity every 4 hours

Ongoing Fluid Management

After initial resuscitation, fluid management depends on the corrected serum sodium level:

• If corrected serum sodium is low: Continue 0.9% NaCl at 4-14 ml/kg/hour 2
• If corrected serum sodium is normal or elevated: Switch to 0.45% NaCl at 4-14 ml/kg/hour 2

Sodium Correction Rate

• Maximum correction rate: 8 mmol/L in 24 hours 1
• Initial target for severe symptoms: 6 mmol/L correction in first 6 hours 1
• Avoid rapid correction to prevent osmotic demyelination syndrome

Electrolyte Supplementation

• Once renal function is assured, add potassium to IV fluids:
  • 20-30 mEq/L potassium (2/3 KCl and 1/3 KPO4) 2
• Continue IV fluids (3-4 L isotonic saline or 5% dextrose in isotonic saline) at a slower rate for 24-48 hours after initial resuscitation 1

Transitioning to Maintenance Fluids

• Once serum glucose reaches 250 mg/dl in diabetic patients, change fluid to 5% dextrose and 0.45-0.75% NaCl with appropriate potassium 2
• Restart mineralocorticoid replacement (fludrocortisone) when hydrocortisone dose falls below 50 mg/day 1
• Taper parenteral glucocorticoids over 1-3 days as clinical condition improves 1

Pitfalls to Avoid

1. Delaying hydrocortisone administration while waiting for diagnostic test results 1
2. Fluid restriction in adrenal crisis patients, which can worsen hypovolemia 1
3. Overly rapid sodium correction (>8 mmol/L per 24 hours) which may result in osmotic demyelination syndrome 1, 3
4. Overlooking the need to restart mineralocorticoid replacement when hydrocortisone dose is reduced 1
5. Failing to monitor for water diuresis (sudden decrease in urine specific gravity ≥0.010), which can lead to overcorrection 1

Special Considerations

• Patients with adrenal insufficiency are at particularly high risk for developing hyponatremia and require isotonic IVFs with close monitoring of fluid quantity 2
• If sodium increases too rapidly, consider administering hypotonic fluids or desmopressin to slow correction 1
• Resume oral hydrocortisone and fludrocortisone when patient can tolerate oral intake 1

By following this algorithm for IV fluid management in Addisonian crisis with hyponatremia, you can effectively address both the hormone deficiency and electrolyte abnormalities while avoiding potential complications.