Examination

Sodium, creatinine (eGFR), calcium, magnesium, alkaline phosphatase, bicarbonate, hemoglobin, MCV, erythrocytes, leukocytes, thrombocytes, haptoglobin, reticulocytes (hemolysis-index)

Rationale

High potassium is usually observed in case of an abnormal renal function (Stuart and Smellie, 2007).

High potassium appears as a side effect of aldosterone inhibitors (such as Spironolactone) used to treat proteinuria. Especially in combination with an ACE-inhibitor or aldosterone inhibitor (Kooter and Smulders, 2009).

High potassium, due to carry-over potassium-EDTA, as indicated by a potential decrease in calcium, magnesium, and alkaline phosphatase (enzyme contains zinc that is removed by EDTA) (Cornes et al., 2008).

Falsely elevated potassium: due to pre-analytical factors like repeatedly making a fist, potassium-EDTA contamination, cooling of the blood sample, delayed processing, thrombocytosis, leukocytosis (can also cause hypokalemia). Measure hemoglobin, MCV, erythrocytes, leukocytes, thrombocytes, haptoglobin, reticulocytes, hemolysis-index (Stuart and Smellie, 2007; Seamark et al., 1999).

Remarks

• Possibly respiratory acidosis (causing high bicarbonate). This can induce hyperkalemia.
• Possibly metabolic acidosis due to renal disorders (causing low bicarbonate). This can contribute to hyperkalemia.
• Side effects of drugs. Cave potassium sparing diuretic (Spironolactone) in combination with an ACE-inhibitor.
• Isolated elevation of potassium. Can be an artefact due to leaving tourniquet on too long or muscle activity with tourniquet on. Consider to repeat the examination.

Example