Written by Vivian Lei
There is rarely any need to repeat potassium testing when the laboratory reports hyperkalemia on a hemolyzed sample in a child with a normal blood urea nitrogen (BUN) and creatinine (Cr).
Why does this matter?
Pseudohyperkalemia is the false elevation of a serum in vitro potassium level due to hemolysis of blood cells during the drawing or processing of blood, and it can be more common in infants or toddlers due to smaller veins, more adipose tissue, and poor cooperation with phlebotomy or IV placement. Is a repeat sample necessary when there is hyperkalemia found in a hemolyzed sample?
Oh K+! Oh K+!
In this 5 year retrospective analysis of pediatric ED patients with elevated potassium in samples reported to be hemolyzed, charts were reviewed and assessed for several variables. A total 187 patients were included. Of the 145 children with hemolyzed hyperkalemia, 142 (97.9%) had a normal repeat potassium level. Three children (2.1%) had true hyperkalemia: one had known chronic renal failure and was referred to the ED due to concern for electrolyte abnormalities; the other 2 patients had diabetic ketoacidosis (DKA). Each year of increased age was the only factor significantly associated with an increased odds of true hyperkalemia (OR 1.24). Underlying medical conditions, degree of hemolysis, initial potassium level, and abnormal BUN/Cr ratio were not associated with odds of true hyperkalemia. The authors propose that in patients without expected electrolyte abnormalities and normal BUN and Cr values, it appears safe to defer repeat sampling to confirm potassium levels when the lab reports hyperkalemia in a hemolyzed sample.
Hyperkalemia in a Hemolyzed Sample in Pediatric Patients: Repeat or Do Not Repeat? Pediatr Emerg Care. 2023 Jan 1;39(1):e1-e5. doi: 10.1097/PEC.0000000000002857. Epub 2022 Sep 29.