Pseudohyponatremia caused by hypercholesterolemia: a rare ca
Pseudohyponatremia represents an artifactual reduction of blood (whole blood, serum or plasma) sodium concentration measured with indirect ion selective electrode (ISE) method. One mechanism of such artifacts is usually due to an abnormal increase in lipids or protein, the non-aqueous components of blood, that result in errors due to water displacement artifacts.

Other mechanisms to cause pseudohyponatremia may be associated with monoclonal proteins when a sample’s hyperviscosity causing aspiration errors. In classic hyperlipidemia (hypertriglyceridemia) induced hyponatremia, several equations have been published to correct errors in serum potassium, chloride, and sodium measurements.

One such equation is: Corrected Na+ = Measured Na+ + [{[0.21 × triglycerides (g/L)] − 0.6} × (Na+ /100)]. Using this equation, the estimated decrease of plasma sodium concentration could be as low as 3.9 mmol/L in a sample with triglyceride concentration of 1500 mg/dL (15 g/L) and sodium concentration of 130 mmol/L.

Published in the journal KI reports, the authors present a case of a 41-year-old man who developed pseudohyponatremia due to hypercholesterolemia with concomitant hypertriglyceridemia and hyperglycemia. The hyponatremia was not fully accounted for by the true dilutional hyponatremia due to hyperglycemia, and examination of the sample revealed that hypercholesterolemia is the culprit for the pseudohyponatremia.

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