Falsely High Plasma Potassium Values in Patients with Hyperaldosteronism

Primary Aldosteronism: Changing Definitions and New Concepts of Physiology and Pathophysiology Both Inside and Outside the Kidney

“…Japanese workers have recently reported on the use of "super-selective" AVS, in which different branches of the adrenal vein are selectively cannulated, permitting comparison of aldosterone production by different regions within a gland (59,60). Although requiring a considerable increase in the duration of the procedure, the potential advantage is that small aldosterone-producing lesions can be localized with sufficient resolution to permit removal by partial, rather than total unilateral, adrenalec- …”

“…This can be avoided by correcting hypokalemia with supplemental slow-release potassium chloride tablets before ratio measurement. The presence of hypokalemia can be obscured, however, if care is not taken during sample collection to avoid false elevations of potassium concentrations (59). Common contributors to this phenomenon include 1) fist clenching, which drives potassium out of the muscles and into the blood; 2) failure to release the torniquet while blood is being collected; 3) "difficult" sampling which can causes hemolysis; 4) the use of Vacutainers (which can also cause hemolysis) rather than syringes; 5) failure to separate plasma from cells within 30 min of blood collection, which allows potassium to leave the red blood cells as their metabolism slows down; and 6) measurement of potassium in serum rather than plasma, which results in higher levels due to release of potassium from the cells during clotting (59, 121).…”

Iatrogenic Worsening of Hypokalemia and Neuromuscular Paralysis Associated with the Use of Glucose Solutions for Potassium Replacement in a Young Woman with Licorice Intoxication and Furosemide Abuse

“…It is possible that this young woman had more severe hypokalemia than the initial potassium level indicated because of ''pseudohyperkalemia'' due to fist clenching during the blood draw, [15][16][17][18] but this hypothesis appears unlikely because at our institution nurses and physicians carefully instruct patients not to clench their fists during blood sampling. None of the precautions necessary at the time of blood sampling to ensure an accurate measurement of potassium levels was neglected and other potential causes of spurious elevations of potassium concentrations, such as orthostasis and hemolysis, 18 were excluded because the patient was lying when blood was drawn and the laboratory did not report the presence of hemolysis in the patient's samples.…”

Is There an Unrecognized Epidemic of Primary Aldosteronism? (Pro)

“…For example, PA has been confirmed in patients with plasma aldosterone levels as low as 9 ng/dL. 27 Falsely high serum potassium levels can occur if patients are asked to repeatedly clinch their fists to facilitate blood collection, which, in turn, may obscure evidence of PA. 28,29 To avoid such an effect, blood should ideally be collected without use of this maneuver.…”