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Electrolytes & Minerals

Sodium (Na⁺)

Normal range 135–145 mEq/L (135–145 mmol/L SI). Specimen: Serum or plasma.

Also known as: serum sodium, na.

135–145 mEq/LCritical: read below

Reference range

ConventionalmEq/L
135145
SImmol/L
135145
SpecimenSerum or plasma
Conventional range135–145 mEq/L
SI range135–145 mmol/L
Conversion factor×1 (conventional → SI)
Critical value< 120 or > 160 mmol/L (seizure and neurologic risk)
PanelElectrolytes & Minerals

Convert any Sodium (Na⁺) result between units on the unit converter.

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.

A commonly taught critical (panic) value is < 120 or > 160 mmol/L (seizure and neurologic risk). Critical results are reported to the provider immediately under your facility's policy.

Source: Adult reference values compiled from Pagana & Pagana, Mosby's Diagnostic and Laboratory Test Reference, and Fischbach & Dunning, A Manual of Laboratory and Diagnostic Tests. Reference ranges vary by laboratory, method, age, sex, and population — always use the range printed on the actual result.

Above the range

Common causes of a high Sodium (Na⁺)

  • Water loss / dehydration
  • Diabetes insipidus
  • Excess sodium intake
  • Hyperaldosteronism

Below the range

Common causes of a low Sodium (Na⁺)

  • SIADH
  • Heart failure or cirrhosis (dilutional)
  • Diuretics
  • Excess water intake

At the bedside

Nursing considerations

  • Correct chronic hyponatremia slowly to avoid osmotic demyelination.
  • Watch for neurologic changes — confusion, seizures — at either extreme.
  • Assess fluid status; sodium disorders are usually water problems.

Study aid

Your notes on Sodium (Na⁺)

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