Hyperkalemia – colloquially called potassium excess – (synonyms: Hyperkalemia syndrome; hyperpotassemia; potassium intoxication syndrome; potassium poisoning syndrome; ICD-10-GM E87.5: hyperkalemia) occurs when the concentration of serum potassium in an adult rises above a value of 5-5.5 mmol/l (in children from 5.4 mmol/l).
Hyperkalemia can be classified into different degrees of severity:
- Mild: 5.5-5.9 mmol/l
- Moderate: 6.0-6.4 mmol/l
- Severe: ≥ 6.5 mmol/l
Pseudohyperkalemia, i.e., a falsely high serum potassium level, occurs when either erythrocytes (red blood cells), leukocytes (white blood cells), or platelets lyse (dissolve “in the test tube”) in vitro and release their potassium into the serum (hemolysis/dissolution of red blood cells). Other causes of pseudohyperkalemia include the occurrence of leukocytosis (> 50,000 leukocytes/mm3), hereditary spherocytosis (spherocytic anemia), incorrect blood collection (venous stasis for too long → hemolysis), or storage of the blood for too long after blood collection (leading to an artificial increase in potassium levels).
Frequency peak: the maximum occurrence of hyperkalemia is in middle to old age.
The prevalence (frequency of illness) in emergency patients ranges from 1.8-10.4%.
The incidence (frequency of new cases) of hyperkalemia in the general population is unknown.
Course and Prognosis: Mild hyperkalemia is usually asymptomatic. High concentrations of 6.5 mmol/L or more (= acute hyperkalemia), on the other hand, are potentially life-threatening and therefore an emergency. They manifest themselves in muscle weakness, paralysis, diarrhea (diarrhea), metabolic acidosis (metabolic acidosis), cardiac arrhythmias (see under Medical Device Diagnostics/ECG: from a decrease in atrial activity, to ventricular fibrillation and to asystole), cardiac arrest, and in the worst case, a fatal outcome (death) is possible. Above a serum potassium level of 5.5 mmol/l, increased mortality (number of deaths in a given period of time, based on the number of the population in question) is to be expected. In hypertensive patients, this is already the case from 5.0 mmol/l. The mortality rate among hospitalized patients due to hyperkalemia varies from 1.7% to 41%.
Comorbidities (concomitant diseases): Hyperkalemia is common in elderly patients with renal disease. In 33% to 83% of cases, renal insufficiency (process leading to a slowly progressive reduction in renal function) or acute renal failure is present. Medications often play a role (see “Causes” below).
