Hyperkalaemia – harmless artefact or medical emergency?

Elevated potassium is one of the most vexing problems faced by a clinician because of the difficulty knowing whether an elevated level (for example, 7.5mmol/L) is a harmless artefact or imminently lethal hyperkalaemia.

The clinical background is critical to interpretation.

You’re almost there! Just or sign up now to access your educational resources.

Possible collection issues affecting serum potassium

Difficult collection

The two main ways a collection can cause elevated potassium are:

Prolonged tourniquet application with hand-clenching (‘making a fist’). Asking patients to clench their fist increases potassium by 2mmol/L, due to release from muscles. With repeated clenching the elevation can be even more (>0.5mmol/L).
Damage to red cells (haemolysis) g. microcollects, heel pricks. With more severe haemolysis the result will often be uninterpretable. A second ...