Key Takeaways

Pseudohyperkalemia is an artificial increase in serum potassium due to the release of potassium from tissue or blood cells during or after venipuncture.

Pseudohyperkalemia is often defined as and characterized by marked elevation of serum potassium levels (>0.4 meq/L [mmol/L]) as compared to the normal plasma potassium concentration in the absence of clinical evidence of electrolyte imbalance..

Reverse pseudohyperkalemia is defined as falsely elevated potassium levels in plasma samples as compared to serum. 

Common causes of pseudohyperkalemia include a factors and variables during and after blood collection (release of potassium from muscle from fist clenching while preventing potassium clearance with a tourniquet, long transport time, cooling of blood sample) and by medical conditions associated with a marked increase in the leukocyte, platelet, or erythrocyte count, especially in the context of hematological malignancies that can render the abnormal cells especially fragile. 

The mechanisms of elevation of potassium involves the release of potassium from cells (tissue cells or blood cells) during the processes of specimen collection and clot formation.  

Suspect diagnosis of pseudohyperkalemia in patient with hemolyzed serum sample or with marked leukocytosis or thrombocytosis and a high serum potassium level who lack clinical or ECG evidence of hyperkalemia and have no obvious identifiable cause of hyperkalemia.

Confirm diagnosis of pseudohyperkalemia by demonstrating normal potassium level in plasma (collected in lithium heparin) or ABG syringe (whole blood) flushed with heparin (potassium levels measured in whole blood and plasma have been shown to be essentially same).

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