Accuracy of Hemolyzed Potassium Levels in the Emergency Department

Abstract

Introduction: In the emergency department (ED), pseudohyperkalemia from hemolysis may indirectly harm patients by exposing them to increased length of stay, cost, and repeat blood draws. The need to repeat hemolyzed potassium specimens in low-risk patients has not been well studied. Our objective was to determine the rate of true hyperkalemia among low-risk, adult ED patients with hemolyzed potassium specimens. Methods: We conducted this prospective observational study at two large (129,000 annual visits) academic EDs in the mid-Atlantic. Data were collected from June 2017-November 2017 as baseline data for planned departmental quality improvement and again from June 2018-November 2018. Inclusion criteria were an initial basic metabolic panel in the ED with a hemolyzed potassium level > 5.1 milliequivalents per liter that was repeated within 12 hours, age ≥18, and bicarbonate (HCO 3) > 20. Exclusion criteria were age > 65, glomerular filtration rate (GFR) < 60, creatine phosphokinase > 500, hematologic malignancy, taking potassium-sparing or angiotensin-acting agents, or treatment with potassium-lowering agents (albuterol, insulin, HCO 3 , sodium polystyrene sulfonate, or potassium-excreting diuretic) prior to the repeat lab draw.

Pseudohyperkalemia related to blood sampling at the University Hospital Center Professor Zafisaona Gabriel Mahajanga

“…Pseudohyperkalemia may be secondary to the locoregional release of potassium by muscle cells during sampling following the application of a tourniquet that is too tight or for more than one minute, to the clenching of the fist or pumping maneuver, and to tapping on the puncture site especially when the collection is difficult [11] [12] [13] [14]. In our case, the pseudohyperkalemia linked to the tourniquet fitting for more than one minute was 42.9% (n = 6) and that linked to the difficult harvesting was 14.3% (n = 2).…”

“…Pseudohyperkalemia may also be linked to the cellular release of potassium in the collection tube during hemolysis, major leukocytosis or thrombocytosis, or late centrifugation [14] [17] [18]. In vitro hemolysis due to poor collection / handling technique and delayed separation of plasma / serum from the whole blood sample are among the most common causes of pseudohyperkalemia [19].…”