title: Do hemolyzed potassium specimens need to be repeated?
abstract: BACKGROUND
  In the emergency department (ED), hyperkalemia in the presence of hemolysis is common. Elevated hemolyzed potassium levels are often repeated by emergency physicians to confirm pseudohyperkalemia and to exclude a life-threatening true hyperkalemia.
  
  
  OBJECTIVE
  We hypothesize that in patients with a normal renal function, elevated hemolyzed potassium, and normal electrocardiogram (ECG), there may not be a need for further treatment or repeat testing and increased length of stay.
  
  
  METHODS
  Data were prospectively enrolled patients presenting to the ED from July 2011 to February 2012. All adult subjects who had a hemolyzed potassium level ≥ 5.5 mEq/dL underwent a repeat potassium level and ECG. The incidence of true hyperkalemia in this population was measured.
  
  
  RESULTS
  A total of 45 patients were enrolled. The overall median age was 52 years (range 25-83 years); 22 were female (49%). In patients with hyperkalemia on initial blood draw and glomerular filtration rate (GFR) ≥ 60 (n = 45), the negative predictive value was 97.8% (95% confidence interval [CI] 88.2-99.9%). When patients had hyperkalemia on initial blood draw, GFR ≥ 60, and a normal ECG (n = 42), the negative predictive value was 100% (95% CI 93.1-100%).
  
  
  CONCLUSIONS
  In the setting of hemolysis, GFR ≥ 60 mL/min in conjunction with a normal ECG is a reliable predictor of pseudohyperkalemia and may eliminate the need for repeat testing. In patients with a normal GFR who are otherwise deemed safe for discharge, our results indicate there is no need for repeat testing.
authors.affiliation: Department of Emergency Medicine, Staten Island University Hospital, Staten Island, New York.
authors.forename: Boris
authors.initials: B
authors.lastname: Khodorkovsky
authors.affiliation: Department of Emergency Medicine, Staten Island University Hospital, Staten Island, New York.
authors.forename: Bartholomew
authors.initials: B
authors.lastname: Cambria
authors.affiliation: Biostatistics Unit, Feinstein Institute for Medical Research, Manhasset, New York.
authors.forename: Martin
authors.initials: M
authors.lastname: Lesser
authors.affiliation: Department of Emergency Medicine, Staten Island University Hospital, Staten Island, New York.
authors.forename: Barry
authors.initials: B
authors.lastname: Hahn
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004562:Electrocardiography; D004636:Emergency Service, Hospital; D005260:Female; D005919:Glomerular Filtration Rate / Q000502:physiology; D006461:Hemolysis / Q000502:physiology*; D006801:Humans; D006947:Hyperkalemia / Q000453:epidemiology / Q000503:physiopathology*; D015994:Incidence; D008297:Male; D008875:Middle Aged; D011188:Potassium / Q000097:blood*; D011237:Predictive Value of Tests; D011446:Prospective Studies
chemical_list: D011188:Potassium
keywords: emergency department testing; hyperkalemia; laboratory; pseudohyperkalemia; resource utilization