Errors in potassium measurement: a laboratory perspective for the clinician

Area of Science:

• Clinical Chemistry
• Laboratory Medicine
• Internal Medicine

Background:

• Pseudohyperkalemia, characterized by falsely elevated serum potassium, is typically identified by laboratory or clinical staff.
• However, factors causing pseudohyperkalemia can also mask true hypokalemia, leading to misdiagnosis.
• These masked hypokalemia cases present a diagnostic challenge, often requiring high clinical suspicion.

Purpose of the Study:

• To discuss the causes and mechanisms of spuriously elevated serum potassium (pseudohyperkalemia).
• To highlight how these factors can mask true hypokalemia.
• To review current recommendations for minimizing measurement errors and discuss "reverse" pseudohyperkalemia.

Main Methods:

• Literature search of PubMed using terms: "pseudohyperkalemia," "reverse pseudohyperkalemia," "factitious hyperkalemia," "spurious hyperkalemia," and "masked hypokalemia."
• Review of relevant articles to identify causes, mechanisms, and diagnostic challenges.

Main Results:

• Identified common laboratory and pre-analytical factors contributing to pseudohyperkalemia.
• Demonstrated how these same factors can lead to falsely normal potassium readings in hypokalemic patients.
• Discussed the concept of "reverse" pseudohyperkalemia and the utility of correction factors.

Conclusions:

• Spurious elevations in serum potassium can obscure true hypokalemia, necessitating clinical vigilance.
• Understanding the mechanisms of pseudohyperkalemia is crucial for accurate potassium level assessment.
• Implementing strategies to minimize measurement errors is essential for reliable diagnostic results.