← Diagnosis and Management Guides
Hyponatremia
Key considerations: Severe hyponatremia with seizures/AMS, Cerebral edema, Osmotic demyelination from overcorrection
Cannot miss
- Severe hyponatremia with seizures/AMS
- Cerebral edema
- Osmotic demyelination from overcorrection
Likely diagnoses
- SIADH
- Heart failure
- Cirrhosis
- Thiazide diuretic
- Psychogenic polydipsia
Red flags
- Na <120
- Seizures
- Altered mental status
- Rapid onset (<48hr)
Workup
- history: Medications (thiazides, SSRIs), fluid intake, symptoms of underlying cause; exam: Volume status assessment (euvolemic, hypovolemic, hypervolemic); labs: BMP, serum osmolality, urine osmolality, urine sodium, TSH, cortisol; imaging: Head CT if AMS or seizures; bedside: Volume status assessment
Management
- immediate: Symptomatic (seizures/AMS): 3% hypertonic saline 100mL IV over 10min, repeat x2 if needed; Target 4-6 mEq/L increase in first 6 hours; general: Max correction rate: 8-10 mEq/L in 24 hours (risk of osmotic demyelination); Hypovolemic: NS; Euvolemic (SIADH): fluid restriction, consider tolvaptan; Hypervolemic: fluid restriction + diuresis
Disposition
- admit: Na <125, symptomatic, acute onset, need for hypertonic saline; discharge: Mild chronic hyponatremia with identified cause and follow-up; consults: Nephrology for severe or refractory cases
Clinical pearls
- Overcorrection of chronic hyponatremia causes osmotic demyelination syndrome (central pontine myelinolysis)
- SIADH diagnostic criteria: euvolemic, urine osm >100, urine Na >40, normal thyroid/adrenal function
Source and review
- European Hyponatremia Guidelines 2014. Last reviewed: 2024-11-01