Reverse pseudohyperkalemia is more than leukocytosis: a retrospective study

Pseudohyperkalemia in pediatric patients with newly diagnosed hematological malignancies

Patients with newly diagnosed hematological malignancies often present with a considerable cellular burden, leading to complications including hyperkalemia. However, pseudohyperkalemia, arising from in vitro cell lysis, can pose challenges in clinical practice. Although pseudohyperkalemia is frequently reported in adult hematological malignancies, its occurrence in pediatric patients is underreported, and its incidence in this demographic remains unclear. We retrospectively reviewed the medical records of pediatric patients who received a new diagnosis of hematological malignancies from 2011 to 2022 at Taichung Veterans General Hospital. Hyperkalemia was defined by a serum or plasma potassium level exceeding 5.5 mEq/L. Pseudohyperkalemia was defined by 1) a potassium decrease of over 1 mEq/L in within 4 h without intervention or 2) the absence of electrocardiography changes indicative of hyperkalemia. Cases with apparent red blood cell hemolysis were excluded. A total of 157 pediatric patients with a new diagnosis of hematological malignancies were included, 14 of whom exhibited hyperkalemia. Among these 14 cases, 7 cases (4.5%) were of pseudohyperkalemia. This rate increased to 21.2% in patients with initial hyperleukocytosis. Pseudohyperkalemia was associated with a higher initial white blood cell count and lower serum sodium level. All episodes of pseudohyperkalemia occurred in the pediatric emergency department, where samples were obtained as plasma, whereas all true hyperkalemia cases were observed in the ordinary ward or intensive care unit, where samples were obtained as serum. Timely recognition of pseudohyperkalemia is crucial to avoiding unnecessary potassium-lowering interventions in pediatric patients with newly diagnosed hematological malignancies.

Spurious Electrolyte and Acid-Base Disorders in the Patient With Cancer: A Review

Electrolyte and acid-base disorders are frequently encountered in patients with malignancy, either due to cancer itself or as a complication of its therapy. However, spurious electrolyte disorders can complicate the interpretation and management of these patients. Several electrolytes can be artifactually increased or decreased such that the serum electrolyte values do not correspond to their actual systemic levels, potentially resulting in extensive diagnostic investigations and therapeutic interventions. Examples of spurious derangements include pseudohyponatremia, pseudohypokalemia, pseudohyperkalemia, pseudohypophosphatemia, pseudohyperphosphatemia, and artifactual acid-base abnormalities. Correctly interpreting these artifactual laboratory abnormalities is imperative for avoiding unnecessary and potentially harmful interventions in cancer patients. The factors influencing these spurious results also must be recognized, along with the steps to minimize them. We present a narrative review of commonly reported pseudo electrolyte disorders and describe strategies to exclude erroneous interpretations of these laboratory values and avoid pitfalls. Awareness and recognition of spurious electrolyte and acid-base disorders can prevent unnecessary and harmful treatments.

Pseudohyperkalemia accompanying actual hyperphosphatemia and hypocalcemia in an adolescent with T-lymphoblastic lymphoma

Tumor lysis syndrome (TLS) is a life-threatening condition that may occur in patients with lymphoma, leukemia, or cancers with high cellular burdens. Without appropriate treatment, electrolyte imbalances, namely hyperkalemia, hyperphosphatemia, and hypocalcemia, can be fatal in patients with TLS. In pseudohyperkalemia, concurrent hyperphosphatemia and hypocalcemia can render devising a treatment strategy challenging. We report an adolescent with T-lymphoblastic lymphoma who presented with pseudohyperkalemia but actual hyperphosphatemia and hypocalcemia, to highlight the importance of accurate clinical interpretations of laboratory data in patients with TLS.

Reverse pseudohyperkalemia in a newly diagnosed pediatric patient with acute T-cell leukemia and hyperleukocytosis: a case report and literature review

Background

Hyperkalemia is a serious medical condition that requires immediate intervention. However, pseudohyperkalemia and reverse pseudohyperkalemia are misleading clinical manifestations that can result in incorrect diagnosis and consequent harmful intervention.

Case presentation

An 11-year-old girl manifested an incidental finding of hyperleukocytosis (WBC > 400 × 109/L), with 90% blast cells during routine pre-operative investigations for adenotonsillectomy. Initial investigations demonstrated elevated serum potassium levels (7.5 mmol/L), despite concomitantly normal levels in venous blood gas samples (3.9–4.4 mmol/L) and being clinically stable with normal 12-lead ECG. Surprisingly, plasma potassium level was exacerbated, in comparison to the serum level by > 1 mmol/L. This finding is consistent with reverse pseudohyperkalemia that is associated with hyperleukocytosis in acute leukemia that does not require any active intervention.

Conclusion

This case report emphasizes the significance of interpreting potassium levels accurately, preferably utilizing whole-blood potassium level over serum and plasma level in newly diagnosed leukemia cases with hyperleukocytosis. Additionally, having a high index for the possibility of reverse pseudohyperkalemia, secondary to leakage from fragile leukocytes, avoids unnecessary treatment that might cause harm to the patient.