Pseudohyperkalemia in Serum: A New Insight into an Old Phenomenon

Abstract

Pseudohyperkalemia, a rise in serum potassium concentration with concurrently normal plasma potassium concentration, is an in vitro phenomenon that was first described 50 years ago. It was originally attributed to the release of potassium from platelets during platelet aggregation and degranulation, and a significant correlation between pseudohyperkalemia and platelet count was established. During the last decade, new data were added to this phenomenon. In particular, pseudohyperkalemia was defined when serum potassium concentration exceeded that of plasma by more than 0.4 mmol/L provided that samples are collected under strict techniques, remain at room temperature and are tested within 1 hour from blood specimen collection. Moreover, it is positively correlated to (1) thrombocytosis due to the release of potassium from platelet granules during coagulation, (2) erythrocytosis due to the dilution of the released potassium in smaller volumes of serum, and (3) the presence of activated platelets, which have the capability of aggregation at a higher speed and release more potassium during degranulation. However, pseudohyperkalemia may be "masked" when in a state of hypokalemia because potassium moves back into the intracellular space in vitro, and the phenomenon is ameliorated or even not detected.

Pneumatic transport is critical for leukaemic patients with major leukocytosis: what precautions to measure lactate dehydrogenase, potassium and aspartate aminotransferase?

“…Pseudohyperkalaemia is observed in association with clotted specimen, but gives comparatively minor rises. 4 Other hypothesis have been evoked such as heparinmediated cell membrane damage. 1 Although no clear evidence, as far as we are aware, has been brought that heparin contained in tubes could have damaging effects on normal blood cells, we cannot rule out that it could exert some damaging effects on fragilized membranes.…”

The clinical significance of hyperkalaemia-associated repolarization abnormalities in end-stage renal disease

“…Finally, it cannot be ruled out that different ECG changes for the same potassium reading may occasionally be due to erroneous blood sampling. Haemolysis, leucocytosis, thrombocytosis and inflammation can produce pseudohyperkalaemia [46].…”

Postsplenectomy thrombocytosis with pseudohyperkalaemia

“…As such, it is diagnosed when the difference between serum and plasma potassium is greater than 0.4 mmol/L in the presence of raised serum potassium levels 5 6. We extend this definition to include the absence of ECG changes, absence of clinical manifestations of electrolyte imbalance and persistence of serum hyperkalaemia despite empirical treatment.…”