Sodium
Background
- Most abundant extracellular cation; key regulator of plasma osmolality and fluid balance
Normal Values
- Normal: 136-145 mEq/L
- Hyponatremia: <136 mEq/L
- Hypernatremia: >145 mEq/L
Interpretation
- Hyponatremia is the most common electrolyte abnormality in hospitalized patients
- Symptoms typically develop when Na <125 mEq/L or with rapid decline (headache, confusion, seizures, coma)
- Correct chronic hyponatremia slowly: limit correction to <8-10 mEq/L per 24 hours to avoid osmotic demyelination syndrome
- Pseudohyponatremia can occur with hyperglycemia; corrected Na = measured Na + 1.6 mEq/L for every 100 mg/dL glucose above normal[1]
- Hypernatremia is almost always due to free water deficit
See Also
References
- ↑ Hillier TA, et al. Hyponatremia: evaluating the correction factor for hyperglycemia. Am J Med. 1999; 106(4):399-403. PMID 10225241.