[Must we always treat hyperkalaemia?].

Area of Science:

• Clinical Medicine
• Hematology
• Laboratory Medicine

Background:

• Pseudohyperkalemia is a laboratory artifact causing falsely elevated serum potassium levels.
• It is often associated with conditions characterized by elevated platelet counts, such as myeloproliferative disorders.
• Accurate differentiation from true hyperkalemia is crucial for appropriate patient management.

Observation:

• A 66-year-old male with a myeloproliferative disorder and thrombocythaemia presented with a serum potassium level of 6.4 mmol/L.
• Renal function and acid-base balance were normal, raising suspicion for pseudohyperkalaemia.
• Subsequent measurements revealed a significant difference between serum (mean 6.27 mmol/L) and plasma (mean 4.10 mmol/L) potassium levels.

Findings:

• The patient's thrombocythaemia led to in vitro potassium release from platelets during blood coagulation.
• This artifactual increase in serum potassium mimicked true hyperkalemia.
• Plasma potassium levels, measured in lithium heparin tubes, accurately reflected the patient's true potassium status.

Implications:

• Increased awareness of pseudohyperkalaemia in thrombocythaemia is essential for clinicians and laboratory professionals.
• Distinguishing pseudohyperkalaemia from true hyperkalemia can prevent potentially harmful and unnecessary treatments.
• This case underscores the importance of considering pre-analytical variables in interpreting laboratory results, especially in hematological conditions.