Errors of Classification With Potassium Blood Testing: The Variability and Repeatability of Critical Clinical Tests

Variability of Potassium Blood Testing: Imprecise Nature of Blood Testing or Normal Physiologic Changes?

“…The reliability and precision of monitoring serum potassium level are the essential issues delineated in the study by Friedman et al in this issue of Mayo Clinic Proceedings. 1 This study demonstrates that there is significant variability and inaccuracy in plasma potassium levels measured in samples of whole blood, despite attempts to standardize conditions under which such measurements are undertaken.…”

Potassium homeostasis and management of dyskalemia in kidney diseases: conclusions from a Kidney Disease: Improving Global Outcomes (KDIGO) Controversies Conference

“…Serum or plasma measurement is acceptable; research reports should state clearly which was used (serum potassium is 0.1-0.7 mmol/l higher). [172][173][174] Point-of-care devices have limited accuracy and precision, [175][176][177][178] which should limit their widespread adoption; however, some devices have been shown to be sufficiently accurate, with mean differences of 0.1 to 0.5 mmol/l when compared with laboratory measurements, to be useful in acute settings. 179,180 A falsely elevated potassium level may occur with fist clenching during the blood draw, mechanical trauma, tourniquet use >1 minute, blood clotting, or elevated white blood cell or platelet counts.…”

Hyperkalemia excursions are associated with an increased risk of mortality and hospitalizations in hemodialysis patients

“…These studies utilized a variety of methodological strategies, including capturing short-term risk within 96 h of K measurement [ 19 ], assessing long-term risk following a single K measurement over multiple years [ 20 ] and investigating 3-month time-averaged serum K [ 21 , 22 ]. Serial K measurements may be more informative than a single K measure by being more sensitive to day-to-day fluctuations in serum K [ 23 , 24 ] and may be aligned with the concept that K excursions may lead to events such as arrhythmias and sudden cardiac death. However, simply averaging recent serum K levels may overlook some at-risk patients because this measure does not reflect variability or potential excursions out of the target range (e.g.…”