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. 2025 Jan;26(1):176-179.
doi: 10.5811/westjem.35286.

Hyperkalemia or Not? A Diagnostic Pitfall in the Emergency Department

Frank-Peter Stephan  1 , Florian N Riede  2 , Luca Ünlü  3   4 , Gioele Capoferri  3 , Tito Bosia  5 , Axel Regeniter  6 , Roland Bingisser  3 , Christian H Nickel  3
Affiliations

Hyperkalemia or Not? A Diagnostic Pitfall in the Emergency Department

Frank-Peter Stephan et al. West J Emerg Med. 2025 Jan.

Abstract

Introduction: Hyperkalemia, a potentially life-threatening electrolyte disturbance, is commonly encountered in the Emergency Department (ED). However, the frequency of factitious hyperkalemia, an artificially elevated potassium level in hyperkalemic ED patients, is unknown. This study aims to detect the rate of factitious hyperkalemia among patients with a potassium concentration of ≥5.0 mmol/l in an all-comer ED population.

Methods: This retrospective, monocentric chart review analyzed data of 2,440 ED patients who presented with a potassium concentration of ≥5.0 mmol/L in their initial whole blood or plasma sample, who also underwent a repeat potassium measurement on the same day. Two groups were established based on potassium levels in the initial and repeat blood tests: 1) True hyperkalemia, characterized by consistently elevated potassium levels in both the initial and repeat samples; and 2) Factitious hyperkalemia, defined by an elevated initial potassium level while the repeat blood test showed a normal potassium level. A subset of factitious hyperkalemia was spurious hyperkalemia. In spurious hyperkalemia, the initial blood sample showed an elevated potassium level with evidence of hemolysis, but a repeat test revealed a normal potassium level without evidence of hemolysis.

Results: Of the 2,440 patients, 1,576 (65%) had true hyperkalemia and 864 (35%) factitious hyperkalemia. Among the 864 patients with factitious hyperkalemia, 597 (69%) displayed hemolysis in their initial blood sample, indicating spurious hyperkalemia due to in-vitro hemolysis.

Conclusion: These data show that about one third of all hyperkalemic blood samples drawn in the ED were due to factitious hyperkalemia. The leading cause of factitious hyperkalemia was spurious hyperkalemia due to in-vitro hemolysis.

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Conflict of interest statement

Conflicts of Interest: By the WestJEM article submission agreement, all authors are required to disclose all affiliations, funding sources and financial or management relationships that could be perceived as potential sources of bias. This work was supported by scientific funds of the Emergency Department of the University Hospital Basel. There are no other conflicts of interest or sources of funding to declare.

Figures

Figure 1.
Figure 1.
Venn diagram illustrating definitions of true hyperkalemia and factitious hyperkalemia. Factitious hyperkalemia is an umbrella term that encompasses various subcategories of falsely elevated potassium levels. These include reverse pseudohyperkalemia (in leukemic patients), pseudohyperkalemia (due to thrombocytosis or erythrocytosis), and spurious hyperkalemia (due to in-vitro hemolysis).
Figure 2.
Figure 2.
Proportions of patients that had true, factitious, and spurious hyperkalemia. Of 2,440 cases with a potassium of ≥5.0 millimoles per liter, 1,576 (65%) had persistent hyperkalemia in a same-day repeat blood test, (ie, they had true hyperkalemia); and 864 (35%) did not show hyperkalemia in a same-day repeat blood test; hence, these patients had factitious hyperkalemia. Of those 864 cases, 597 (69%) showed evidence of hemolysis in their initial blood test; thus, these patients had spurious hyperkalemia due to in-vitro hemolysis. In 267 of the 864 cases of factitious hyperkalemia (31%), no evidence of hemolysis was observed. The reason for the occurrence of factitious hyperkalemia in these cases remains unclear. mmol/L, millimoles per liter.
See this image and copyright information in PMC

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