Potassium (K+) is an electrolyte required to allow normal transmembrane voltage gradients and physiology. This is present in the intracellular and extracellular environments. Once transmembrane voltage gradient is reached at a useful level, this also enables the establishment of action potentials in “excitable membranes” such as the ones that exist in the skeletal, cardiac, and smooth muscle, and the nerve cells.
The K+ levels in the body are regulated by the renal system. The kidneys perform 90% of the K+ excretion while the remaining 10% is excreted through the GI system. Normal serum K+ levels ranges from 3.5-5.0 mEq/L.
Hyperkalemia is defined by serum K+ levels of > 5.5 mEq/L. Excessive K+ level affects the transmembrane gradient and, consequently, the excitable membrane functions in muscle and nerve cells.
It also has several effects on the myocardial electrophysiology that contribute to intracardiac conduction disturbances.
Hyperkalemia can be detected in approximately 10% of patients admitted in the emergency department. To properly treat and manage hyperkalemia, identification of the rate and cause at which K+ serum levels are accrued is vital.
Types of Hyperkalemia
- Mild hyperkalemia – 5.5 – 6.5 mEq/L K+ levels
- Moderate hyperkalemia – 6.5 – 7.5 mEq/L K+ levels
- Severe hyperkalemia – ≥ 7.5 mEq/L K+ levels; fatal, rapid diagnosis and management are essential