Pneumatic tube transport-induced pseudohyperkalemia in patients with extreme leukocytosis: a retrospective study from a single medical center

BACKGROUND

Pseudohyperkalemia (falsely elevated serum potassium) must be distinguished from true hyperkalemia to avoid unnecessary treatment. Some case reports suggest that pneumatic tube transportation may increase the risk of pseudohyperkalemia, but comprehensive research on the topic is lacking. Here, we aimed to assess the association between WBC levels, pneumatic tube transport, and pseudohyperkalemia prevalence.

METHODS

We analyzed 1188 samples collected from 240 patients between 2019 and 2022. Samples with elevated WBC counts (≥ 100 × 103/μL) and potassium levels were included in this study. The method of specimen transportation was documented.

RESULTS

Pseudohyperkalemia was observed (7/390) in specimens transported using pneumatic tubes. No pseudohyperkalemia was identified with manually transported specimens (0/132). Every increase in WBC count by 100 × 103/μL in the specimens multiplied the odds ratio of pseudohyperkalemia by 3.75 when delivered with pneumatic tube. The prevalence of pseudohyperkalemia increased as WBC count increased, especially at WBC counts greater than 200 × 103/μL.

CONCLUSION

Pneumatic tube transport poses a risk for pseudohyperkalemia in patients with extreme leukocytosis. Physicians should anticipate odd potassium levels when interpreting blood test results. Redrawing of blood samples, manual specimen transportation, or point-of-care testing are suggested to prevent further misdiagnosis.

Pseudohyperkalemia in chronic lymphocytic leukemia: Prevalence, impact, and management challenges

The term pseudohyperkalemia refers to a false elevation in serum potassium levels due to potassium release from cells in vitro. Falsely elevated potassium levels have been reported in patients with thrombocytosis, leukocytosis, and hematologic malignancies. This phenomenon has been particularly described in chronic lymphocytic leukemia (CLL). Leukocyte fragility, extremely high leukocyte counts, mechanical stress, higher cell membrane permeability related to an interaction with lithium heparin in plasma blood samples, and metabolite depletion due to a high leukocyte burden have been reported to contribute to pseudohyperkalemia in CLL. The prevalence of pseudohyperkalemia is up to 40%, particularly in the presence of a high leukocyte count (>50 × 109/L). The diagnosis of pseudohyperkalemia is often overlooked, which may result in unnecessary and potentially harmful treatment. The use of whole blood testing and point-of-care blood gas analysis, along with thorough clinical evaluation, may help differentiate between true and pseudohyperkalemic episodes.

The Role of Using Red-Topped - Non-Additive-Containing - Collecting Tube in Diagnosing Pseudohyperkalemia in Chronic Lymphocytic Leukemia

Pseudohyperkalemia in the context of chronic lymphocytic leukemia (CLL) is becoming a common clinical presentation in our daily practice, yet the recognition and the overall approach to this condition remains a challenge as clinicians ponder on whether it's a true rise of serum potassium or not, weighing the risk-benefit ratio of giving the full anti-hyperkalemia measures, dreading the potential iatrogenic hypokalemia if it proves to be a pseudohyperkalemia instead.

[Pseudohyperkalemia and thrombocytosis]

INTRODUCTION

Hyperkalemia is common in medicine and requires rapid management. Besides the easily evoked causes such as renal failure, adrenal insufficiency, cell lysis or iatrogenic causes, false or pseudo-hyperkalemia should not be forgotten.

OBSERVATIONS

Three patients (1 man, 2 women, aged 78, 84, 88) were managed for thrombocytosis (between 1306 and 2404 G/L) and non-symptomatic hyperkalemia (between 6.1 and 7.7mmol/L) are reported. Kalemia on blood collected in heparin tube was normal (4.4-4.6mmol/L). Therefore, no specific treatment for this pseudohyperkalemia was required.

CONCLUSION

The combination of thrombocytosis and non-symptomatic hyperkalemia should suggest the diagnosis of pseudohyperkalemia and should prompt for a control of kalemia on blood collected in heparin tube. The recognition of this diagnosis is important in order to avoid unnecessary and potentially deleterious treatment of hyperkalemia.