Abstract
Falsely elevated potassium levels are common in routine laboratory tests and should be differentiated from true hyperkalemia. If the patient is inappropriately treated for hyperkalemia, the resulting hypokalemia can lead to life-threatening cardiac arrhythmias. We present the case of a 67-year-old woman with a past medical history of stable chronic lymphocytic leukemia, who presented for chest pain and had an elevated potassium level of 5.8 mEq/L, which, upon repeat laboratory testing, was then 6.7 mEq/L. She was initially treated for hyperkalemia. Laboratory test results showed creatine kinase levels at 43 U/L, lactate dehydrogenase levels at 177 U/L, phosphorus levels at 4.5 mg/dL, and uric acid levels at 6.4 mg/dL, indicating no evidence of tumor lysis syndrome. The patient was later diagnosed with reverse pseudohyperkalemia, indicated by falsely elevated plasma potassium levels in the presence of serum potassium levels within normal limits and venous blood gas samples.
Highlights
Elevated potassium levels are commonly seen in routine laboratory tests and physicians should always differentiate false elevated potassium levels from true hyperkalemia
We present a case of a 67-year-old woman with a past medical history of stable chronic lymphocytic leukemia (CLL) for seven years who presented to the emergency department (ED) with chest pain
Heparin has been implicated to play a role in reverse pseudohyperkalemia, as heparinized samples have been shown to have elevated potassium levels when compared to corresponding nonheparinized samples
Summary
Elevated potassium levels are commonly seen in routine laboratory tests and physicians should always differentiate false elevated potassium levels from true hyperkalemia. Lack of filling defect indicates the absence of pulmonary embolism Her cardiac troponin trended negatively over the following 12 hours, and her chest pain was attributed to musculoskeletal etiology. The patient confirmed she was not taking any medicines or herbal supplements at home. To determine the causes of hyperkalemia, further workup for tumor lysis syndrome revealed a creatine kinase level of 43 U/L, lactate dehydrogenase level of 177 U/L, phosphorus level of 4.5 mg/dL, and uric acid level of 6.4 mg/dL, effectively ruling out the condition This was followed by a detailed evaluation for hyperkalemia, which included comparing plasma potassium levels - with and without centrifugation - to serum and venous blood gas levels. We recognized that in our hospital, the ED uses plasma samples while the general medical floors use serum samples for processing blood electrolytes
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