Below the range
Common causes of a low Sodium (Na⁺)
- SIADH
- Heart failure or cirrhosis (dilutional)
- Diuretics
- Excess water intake
Looking for the other direction? See what causes a high Sodium (Na⁺).
All tests · Electrolytes & Minerals · Sodium (Na⁺)
Below the range
What causes a low Sodium (Na⁺)?
Normal range 135-145 mEq/L (135-145 mmol/L SI). Specimen: Serum or plasma. See the full Sodium (Na⁺) reference page for critical values and nursing considerations.
What is the normal range for Sodium (Na⁺)?
The standard teaching reference range for Sodium (Na⁺) is 135-145 mEq/L in conventional units, or 135-145 mmol/L in SI units. This value is measured in serum or plasma.
| Specimen | Serum or plasma |
|---|---|
| Conventional range | 135-145 mEq/L |
| SI range | 135-145 mmol/L |
| Critical value | < 120 or > 160 mmol/L (seizure and neurologic risk) |
| Panel | Electrolytes & Minerals |
Full details, including nursing considerations, on the Sodium (Na⁺) normal range page. Reference ranges vary by laboratory, method, age, sex, and population - always use the range printed on the actual result.
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