Nauru CDS

Electrolyte Correction Protocols

Comprehensive electrolyte management with correction formulas, infusion rates, and calculators

Electrolytes
Na+Sodium

Normal Range: 135-145 mEq/L

Critical High: >160 mEq/LCritical Low: <120 mEq/L
Hypersodiumemia

Serum sodium >145 mEq/L

Mild146-150 mEq/L

Oral free water replacement, investigate cause

Moderate151-159 mEq/L

IV D5W or 0.45% NaCl, monitor Q4-6H

Severe≥160 mEq/L

ICU admission, IV D5W, monitor Q2-4H, correct slowly

Common Causes

  • • Dehydration / free water loss (fever, burns, diarrhea)
  • • Diabetes insipidus (central or nephrogenic)
  • • Excessive hypertonic saline administration
  • • Inadequate free water intake (elderly, altered mental status)
  • • Osmotic diuresis (hyperglycemia, mannitol)
Hyposodiumemia

Serum sodium <135 mEq/L

Mild130-134 mEq/L

Fluid restriction, investigate cause

Moderate125-129 mEq/L

Fluid restriction, consider 3% NaCl if symptomatic

Severe<125 mEq/L

3% hypertonic saline, ICU, monitor Q1-2H

Common Causes

  • • SIADH (syndrome of inappropriate ADH secretion)
  • • Heart failure (dilutional)
  • • Cirrhosis with ascites
  • • Chronic kidney disease
  • • Excessive hypotonic IV fluids
Correction Formulas
Free Water Deficit (Hypernatremia)

FWD (L) = TBW × [(Serum Na / 140) - 1]

TBW = 0.6 × weight (kg) for males, 0.5 × weight for females. Replace 50% in first 24h, rest over 48-72h.

Sodium Deficit (Hyponatremia)

Na deficit (mEq) = TBW × (Target Na - Actual Na)

Target correction: 8 mEq/L per 24 hours maximum. Each 1 L of 3% NaCl contains 513 mEq Na.

Adrogue-Madias Formula

ΔNa = (Infusate Na - Serum Na) / (TBW + 1)

Predicts change in serum Na per 1 liter of infusate. 3% NaCl = 513 mEq/L, 0.9% NaCl = 154 mEq/L, D5W = 0 mEq/L.

Clinical Pearls
  • 💡 Always check serum osmolality to classify hyponatremia (hypotonic, isotonic, hypertonic)
  • 💡 Pseudohyponatremia: elevated lipids or proteins cause falsely low Na on flame photometry
  • 💡 Correct Na for glucose: For every 100 mg/dL glucose above 100, add 1.6 mEq/L to measured Na
  • 💡 Urine Na >20 mEq/L suggests renal salt wasting; <20 suggests extrarenal losses
  • 💡 In beer potomania, Na may correct rapidly with normal diet - monitor closely for ODS