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.
Possible collection issues affecting serum potassium
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 ...