What can cause pseudohyponatremia in patients with nephrotic syndrome?

Pseudohyponatremia occurs when there is a falsely low measurement of serum sodium concentration, typically due to the presence of an excess of non-aqueous components in the serum, such as lipids or proteins. In patients with nephrotic syndrome, there is a significant increase in serum lipids due to the liver compensating for low oncotic pressure resulting from protein loss in the urine. This high lipid level can lead to dilutional effects that interfere with laboratory measurement techniques, often seen in automated analyzers that may calculate sodium concentration based on volume that is artificially influenced by these lipids.

Therefore, in the context of nephrotic syndrome, elevated lipids are a primary cause of pseudohyponatremia, highlighting the importance of considering this phenomenon when evaluating sodium levels in such patients. Understanding this condition allows clinicians to interpret laboratory results accurately and avoid misdiagnosis or premature management based on false lab findings.