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Abstract: PO1920

Pseudohyperkalemia Leading to Pseudohyponatremia in Severe Leukocytosis

Session Information

Category: Onco-Nephrology

  • 1500 Onco-Nephrology

Authors

  • Khan, Hameeda Tayyab, Weill Cornell Medicine, New York, New York, United States
  • Glezerman, Ilya, Memorial Sloan Kettering Cancer Center, New York, New York, United States
Introduction

Electrolyte abnormalities are common in oncologic malignancies. However spurious derangements are rarer. Here we present a case of coexisting reverse pseudohyperkalemia and pseudohypoanatremia in chronic lymphocytic leukemia.

Case Description

An 84 year old male was diagnosed with chronic lymphocytic leukemia after presenting with weight loss and fevers. Labs showed a WBC of 760 K/mcl, Plasma sodium was 133 Meq/L, plasma potassium 8.8 Meq/L, BUN 15mg/dl, Creatinine 2.8 mg/dl and a GFR of 20 ml/min. Urine analysis showed 100 mg/dl of protein, 300 mg/dl of glucose and small blood. Urine sodium of 82 meq/L and osmolality of 444 mosmol/kg with serum osmolality of 300 mosmol/kg. EKG did not show any hyperkalemic changes. He received insulin, dextrose and kayexalate. Repeat plasma potassium was 10.7 Meq/L.
Given high suspicion for reverse pseudohyperkalemia due to leukocytosis, serum labs were sent. Serum potassium was 4.2 Meq/L and serum sodium 134 Meq/L with a concurrent plasma Potassium of >9.0 Meq/L and plasma sodium of 127 Meq/L. The WBC count remained elevated at 693.2 K/mcl. The serum sodium is measured at our institution with direct ion-specific electrode method making derangements from hyperlipidemia and hyperproteinemia unlikely.
Treatment was started with methylprednisolone and Rituximab for CLL. The WBC count trended down from 693 to 339.5 K/mcl. Serum potassium remained stable (3.7-4.9) as well as serum sodium (138-141) with concurrent plasma values decreasing in disparity from potassium >9Meq/L to 4.9 Meq/L and sodium 127 Meq/L to 139 Meq/L as the WBC count decreased.

Discussion

This case portrays a challenging case of reverse pseudohyperkalemia and pseudohyponatremia in severe lymphocytosis. While the phenomenon of pseudohyperkalemia in leukemia/lymphomas is established, reverse pseudohyperkalemia where plasma potassium is falsely elevated compared to normal serum levels is lesser known. Furthermore, no mechanism has been established for pseudohyponatremia in plasma samples compared to serum samples in leukocytosis however it was postulated that sodium levels decrease reciprocally to potassium due to potassium release from the leukocytes. Hence in cases of reverse pseudohyperkalemia serum samples are preferred over plasma samples. Parameters need to be established to avoid treatment of spurious electrolyte disorders to avoid treatments resulting in hypokalemia and hypernatremia.