Severity
- Mild 130–134 · Moderate 125–129 · Severe < 125 mEq/L
- Severe symptoms: seizure, coma, vomiting, obtundation → treat regardless of Na value
- Acute (<48 h) tolerates faster correction than chronic
Symptomatic / severe — 3% NaCl
- 3% NaCl 100 mL IV bolus over 10 min — repeat ×3 PRN until symptoms resolve or Na ↑ 4–6 mEq/L
- Goal: ↑ Na 4–6 mEq/L in first 1–2 h to abort herniation/seizure
- Stop bolus once symptoms resolve — then reassess
Correction limits
- ≤ 8 mEq/L per 24 h (≤ 6 if high risk: chronic, K depletion, liver disease, malnutrition)
- Overcorrection → osmotic demyelination syndrome (ODS)
- If overshoot: D5W 6 mL/kg over 2 h ± DDAVP 2–4 mcg IV to relower
- Recheck Na q2h initially
Workup by volume status
- Hypovolemic: GI/renal loss, diuretics → NS
- Euvolemic: SIADH, hypothyroid, adrenal insuff, polydipsia → fluid restrict
- Hypervolemic: CHF, cirrhosis, nephrotic, AKI → diuresis + fluid restrict
- Check: serum osm, urine osm, urine Na, TSH, cortisol
- Exclude pseudohyponatremia (hyperglycemia, hyperlipidemia, paraproteinemia)
Disposition
- Admit (often ICU): symptomatic, Na < 125, requiring 3%
- Discharge: mild asymptomatic chronic with clear cause + close follow-up