Serum Sodium of 120 mmol/L is Severe Hyponatremia
Yes, a serum sodium level of 120 mmol/L is considered severe hyponatremia. According to current medical guidelines, hyponatremia is classified as mild (130-134 mmol/L), moderate (125-129 mmol/L), and severe (<125 mmol/L) 1.
Classification of Hyponatremia Severity
- Serum sodium <125 mmol/L is classified as severe hyponatremia 1
- Serum sodium 125-129 mmol/L is classified as moderate hyponatremia 1
- Serum sodium 130-134 mmol/L is classified as mild hyponatremia 1
Clinical Significance of Severe Hyponatremia
- Severe hyponatremia (<120 mmol/L) can cause serious neurological symptoms including coma or grand mal seizures 2
- A serum sodium of 120 mmol/L represents severe hyponatremia requiring immediate intervention 3
- In patients with cirrhosis, a serum sodium of 120 mmol/L is found in only 1.2% of patients with ascites, highlighting its rarity and severity 4
- Patients with severe hyponatremia are at increased risk for complications, with sodium levels <130 mmol/L linked to a 60-fold increase in fatality (11.2% versus 0.19%) 3
Management Considerations for Severe Hyponatremia
- For severe hyponatremia (<120 mmol/L), fluid restriction alone is usually insufficient and more aggressive interventions may be necessary 3
- Severe fluid restriction plus albumin infusion may be necessary for severe hyponatremia (<120 mmol/L) 3
- The rate of correction should not exceed 8 mmol/L in 24 hours to prevent osmotic demyelination syndrome 3, 5
- For patients with advanced liver disease, alcoholism, or malnutrition, even more cautious correction (4-6 mmol/L per day) is recommended due to higher risk of osmotic demyelination syndrome 3
Treatment Approach Based on Volume Status
- For hypovolemic severe hyponatremia: discontinue diuretics and administer isotonic saline for volume repletion 3
- For euvolemic severe hyponatremia (SIADH): implement fluid restriction to <1 L/day and consider vasopressin receptor antagonists for resistant cases 3, 6
- For hypervolemic severe hyponatremia (cirrhosis, heart failure): implement fluid restriction to 1-1.5 L/day and consider albumin infusion for cirrhotic patients 3
Common Pitfalls to Avoid
- Overly rapid correction exceeding 8 mmol/L in 24 hours can lead to osmotic demyelination syndrome, particularly in patients with risk factors such as alcoholism, malnutrition, or liver disease 3, 5
- Inadequate monitoring during active correction can lead to complications 3
- Using fluid restriction in cerebral salt wasting can worsen outcomes 3
- Using hypertonic saline in hypervolemic hyponatremia without life-threatening symptoms can worsen edema and ascites 3
In conclusion, a serum sodium of 120 mmol/L is definitively classified as severe hyponatremia and requires careful medical management with appropriate treatment based on the underlying cause and volume status, while ensuring that correction rates remain within safe limits to prevent neurological complications.