What Is Sodium in a Blood Test?
Sodium is the primary electrolyte regulating fluid balance, nerve impulses, and blood pressure.
Normal Range
- 135–145 mEq/L
- Hyponatremia: below 135
- Hypernatremia: above 145
- Severe hyponatremia: below 125 — brain swelling risk
Low Sodium Causes
- Excessive water intake
- Heart failure
- Liver cirrhosis
- SIADH
- Diuretics
- Hypothyroidism
- Adrenal insufficiency
High Sodium Causes
- Dehydration — most common
- Diabetes insipidus
- Excessive salt intake
Symptoms
- Low: headache, confusion, nausea, seizures
- High: thirst, confusion, muscle twitching
- Rapid sodium correction can be dangerous — correct slowly under medical supervision
Source: NLM MedlinePlus, American Association for Clinical Chemistry.
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