Treatment of Pseudohyponatremia
Pseudohyponatremia requires no specific sodium correction as it represents a laboratory artifact rather than a true sodium deficit, and treatment should focus on addressing the underlying cause.
Understanding Pseudohyponatremia
Pseudohyponatremia is a laboratory phenomenon characterized by falsely low serum sodium measurements despite normal effective plasma osmolarity. It occurs in specific clinical scenarios:
- Pseudohyponatremia results from laboratory artifact when sodium is measured by flame photometry or other methods that don't directly measure sodium activity in the water phase of plasma 1
- It commonly occurs in conditions with extreme hyperlipidemia or hyperproteinemia (such as multiple myeloma) 2, 1
- Unlike true hyponatremia, patients with pseudohyponatremia typically don't exhibit symptoms related to low sodium levels 3
Diagnostic Approach
Proper identification of pseudohyponatremia is essential to avoid inappropriate treatment:
- Measure serum osmolality - normal or elevated osmolality with low reported sodium suggests pseudohyponatremia 3
- Consider using ion-selective electrode measurement of sodium, which provides accurate readings even in the presence of hyperlipidemia or hyperproteinemia 2, 1
- Evaluate for conditions associated with pseudohyponatremia:
- Severe hyperlipidemia
- Hyperproteinemia (multiple myeloma, Waldenstrom's macroglobulinemia)
- Hyperglycemia (which causes a different form of laboratory artifact) 3
Treatment Principles
The management of pseudohyponatremia differs fundamentally from true hyponatremia:
- No sodium correction is needed as the actual sodium concentration in the water phase of plasma is normal 1, 4
- Focus treatment on the underlying cause of hyperlipidemia or hyperproteinemia 3
- Avoid inappropriate administration of hypertonic saline or other sodium-raising interventions that could lead to true hypernatremia 1
Common Pitfalls to Avoid
- Misdiagnosing pseudohyponatremia as true hyponatremia and initiating unnecessary fluid restriction or sodium correction 1
- Failing to recognize the laboratory method used for sodium measurement in your facility 1
- Not considering pseudohyponatremia in patients with conditions associated with extreme hyperlipidemia or hyperproteinemia 2, 4
- Overlooking the need to measure serum osmolality to differentiate between true and pseudo-hyponatremia 3
Special Considerations
- In multiple myeloma patients, pseudohyponatremia may resolve with treatment of the underlying disease, as demonstrated by normalization of sodium levels after chemotherapy 2
- Alternative methods to assess true sodium status include:
Remember that pseudohyponatremia is a laboratory artifact rather than a physiological disturbance, and treating it as true hyponatremia could lead to harmful consequences.