Hyperkalemia breaks down to mean hyper- high; kalium, potassium; -emia, "in the blood" or high potassium in the blood. Potassium in the bloodstream is the K+ ion, not potassium metal, so this illness is one type of electrolyte imbalance. The normal concentration of the potassium ion in blood is 3.5 to 5.3 mmol or milliequivalents per liter (mEq/L). Concentrations of 5.5 mmol and higher describe hyperkalemia. The opposite condition, low blood potassium levels, is termed hypokalemia. Mild hyperkalemia typically isn't identified except through a blood test, but extreme hyperkalemia is a medical emergency that can result in death, usually from heart arrhythmia.
The symptoms of elevated potassium are not specific to the condition. Mainly the effects are on the circulatory and nervous system. They include:
- heart palpitations
Causes of Hyperkalemia
Hyperkalemia results when too much potassium is taken into the body, when cells massively release potassium into the bloodstream, or when the kidneys can't properly excrete potassium. There are numerous causes of hyperkalemia, including:
- kidney disease
- diabetes (leading to nephropathy)
- medications that affect urination (NSAIDS, diuretics, antibiotics, etc.)
- diseases associated with a mineralocorticoid deficiency
- massive blood transfusion
- any major tissue damage, whether it be from injury (burns, serious wounds) or medical treatment (notably chemotherapy)
- excessive dietary intake of potassium-rich foods (e.g., salt substitute, bananas)
- intentional hyperkalemia as the last step of lethal injection, to disrupt and stop the heart
Not that it's highly unusual for a person with ordinary kidney function to "overdose" on potassium from foods. Excess potassium resolves itself if the kidneys are able to process an overload. If the kidneys are damaged, hyperkalemia becomes an ongoing concern.
In some cases, it's possible to prevent potassium buildup by limiting dietary intake of potassium-rich foods, taking diuretics, or ending a medication that causes a problem.
Treatment depends on the cause and severity of hyperkalemia. In a medical emergency, the goal is to shift the potassium ion from the bloodstream into cells. Injecting insulin or salbutamol temporarily lowers serum potassium levels.