TY - JOUR
AU - Kellogg,, Mark
AB - Case Description Consecutive laboratory results for a 6-year-old girl at a cancer clinic consistently showed contradictory potassium concentrations in her plasma and whole blood specimens. Consultation with the bedside nurse and repeat blood sampling ruled out the possibility of sample contamination. Electrocardiogram monitoring revealed normal cardiac function. Questions Which measured potassium concentration reflects the physiological potassium concentration? What caused the discrepancy in results? The answers are below. Answers The patient had normal cardiac function; therefore, the high plasma potassium likely did not reflect her true physiological condition. The measured whole blood potassium concentration was low, but normal cardiac function can be observed with a potassium concentration of 3.00 mmol/L. Pseudohyperkalemia is commonly attributed to the release of potassium from platelets during coagulation in serum; however, since the pseudohyperkalemia was in plasma and the platelet count was below normal, this was an unlikely cause. High white blood cell (WBC) concentrations have been reported to cause pseudohyperkalemia in serum; however, the use of plasma was thought to prevent this problem. This patient had acute lymphoblastic leukemia (ALL) with an unusually high WBC concentration (525.25 × 103 cells/μL) and blast cells (86%). These fragile cells could lyse during transport or centrifugation and artificially increase the potassium concentration in plasma. A longer turnaround time for the plasma specimen (approximately 45 min for plasma vs approximately 15 min for whole blood) may have further increased cell lysis and hence the pseudohyperkalemia. Plasma (spun down from a whole blood specimen) measured approximately 15 min after sample collection demonstrated a normal potassium concentration, and as the WBC concentration decreased, the potassium concentrations returned to normal in plasma and whole blood specimens. This case clearly illustrates the potential problems in measuring potassium in patients with extremely high WBC concentrations. Table 1. Analyte . Results . Reference interval . Potassium (heparinized plasma) (Roche cobas c501) 9.83 mmol/L 3.20–4.50 mmol/L Potassium (heparinized whole blood) (Radiometer ABL800) 3.00 mmol/L 3.20–4.50 mmol/L Analyte . Results . Reference interval . Potassium (heparinized plasma) (Roche cobas c501) 9.83 mmol/L 3.20–4.50 mmol/L Potassium (heparinized whole blood) (Radiometer ABL800) 3.00 mmol/L 3.20–4.50 mmol/L Open in new tab Table 1. Analyte . Results . Reference interval . Potassium (heparinized plasma) (Roche cobas c501) 9.83 mmol/L 3.20–4.50 mmol/L Potassium (heparinized whole blood) (Radiometer ABL800) 3.00 mmol/L 3.20–4.50 mmol/L Analyte . Results . Reference interval . Potassium (heparinized plasma) (Roche cobas c501) 9.83 mmol/L 3.20–4.50 mmol/L Potassium (heparinized whole blood) (Radiometer ABL800) 3.00 mmol/L 3.20–4.50 mmol/L Open in new tab © 2009 The American Association for Clinical Chemistry This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model)
TI - What Is Your Guess? Hyperkalemia or Hypokalemia?
JO - Clinical Chemistry
DO - 10.1373/clinchem.2009.132613
DA - 2009-11-01
UR - https://www.deepdyve.com/lp/oxford-university-press/what-is-your-guess-hyperkalemia-or-hypokalemia-bS0aOs94a7
SP - 2068
VL - 55
IS - 11
DP - DeepDyve
ER -