Hyperkalemia or Not? A Diagnostic Pitfall in the Emergency Department

Area of Science:

• Clinical Pathology
• Emergency Medicine
• Laboratory Medicine

Background:

• Hyperkalemia is a common and potentially dangerous electrolyte imbalance encountered in the Emergency Department (ED).
• The prevalence of factitious hyperkalemia, where potassium levels are artificially elevated, is not well-established in ED populations.
• Understanding the causes of factitious hyperkalemia is crucial for accurate diagnosis and patient management.

Purpose of the Study:

• To determine the incidence of factitious hyperkalemia among patients presenting to the ED with elevated potassium levels (≥5.0 mmol/L).
• To identify the primary causes of factitious hyperkalemia in this patient cohort.

Main Methods:

• A retrospective chart review of 2,440 Emergency Department patients with initial potassium levels ≥5.0 mmol/L.
• Patients underwent repeat potassium measurements on the same day to differentiate true from factitious hyperkalemia.
• Factitious hyperkalemia was defined by an initial high potassium level with a subsequent normal level; spurious hyperkalemia was a subset involving hemolysis.

Main Results:

• A total of 2,440 patients were analyzed, with 1,576 (65%) having true hyperkalemia and 864 (35%) exhibiting factitious hyperkalemia.
• In-vitro hemolysis in the initial sample was identified as the cause in 597 (69%) of the factitious hyperkalemia cases, classifying them as spurious hyperkalemia.

Conclusions:

• Approximately one-third of hyperkalemic blood samples in the ED setting are factitious, not reflecting true hyperkalemia.
• In-vitro hemolysis during blood sample collection or processing is the leading contributor to spurious, factitious hyperkalemia.