Pseudohyperkalemia of Leukemia Patients with Hyperleukocytosis Caused by Pneumatic Tube System

  Objective  To invest the effects of pneumatic tube system(PTS) transportation on blood potassium measurement result in leukemia patients with hyperleukocytosis.

  Methods  Clinical data of four leukemia patients with pseudohyperkalemia detected in emergency laboratory of Peking Union Medical College Hospital in the period from July 2013 to July 2015 were collected and reviewed to retrospectively analyze clinical diagnosis, sample transportation method, white blood cell count, plasma potassium level, arterial whole blood potassium level, partial serum potassium level, chemotherapy, and electrocardiogram.We also collected the above information of 10 cases of infectious disease with leukemoid reaction and 50 cases of non-blood system disease patients with normal white blood cell counts as control group from the same period. We compared the effect of different transportation methods (PTS vs. manual transportation) on blood potassium levels in different white blood cell functional status, sample types, and sample containers.

  Results  In the 4 leukemia patients with high periph- eral blood white cell count(206.8×10⁹/L-652.1×10⁹/L), potassium concentration in lithium-heparin venous blood samples transported by PTS was strikingly elevated (5.9-14.8 mmol/L), while the level of potassium of arterial whole blood and serum samples transported simultaneously by PTS were not influenced. There was no significant effect of PTS on plasma potassium levels of venous and arterial whole blood samples transported by PTS in controls(P > 0.05).

  Conclusion  The plasma potassium level in lithium-heparin venous blood samples of leukemia patients with high peripheral blood white cell count may be elevated if transported by PTS, which will lead to pseudohyperkalemia.