K | Potassium

Potassium (K) – is the most important intracellular cation, playing a crucial role in maintaining cell functions, muscle contractions (especially in the heart), nerve impulse transmission, and the body's water and electrolyte balance. Most of the potassium is found within cells, and its concentration in blood serum, although small, is tightly regulated because any deviation can have serious clinical consequences.

The average potassium concentration in the blood is about 4.5 mmol/l. Values from 3.5 to 5.3 mmol/l are considered normal. Increased concentration is called hyperkalemia, and decreased concentration is called hypokalemia. Both of these electrolyte imbalances can cause dangerous heart rhythm disturbances and even life-threatening cardiac arrest.

Principle of the test: Serum potassium concentration is determined by biochemical methods, most commonly using ion-selective electrodes. Results are presented in millimoles per liter (mmol/l).

Recommendations:

• It is recommended for patients with kidney function disorders, cardiovascular diseases, diabetes, especially those taking insulin or diuretics. The test is also useful for those who engage in intensive sports or physical activity, as well as those at increased risk of dehydration or suspected electrolyte imbalances.
• Hyperkalemia can be caused by kidney failure, tissue breakdown (after injuries or burns), use of certain medications (e.g., ACE inhibitors, potassium-sparing diuretics), adrenal insufficiency, or metabolic acidosis. Hypokalemia is usually due to excessive fluid loss from vomiting, diarrhea, sweating, as well as the use of diuretics, laxatives, insulin excess, malnutrition, or alcohol consumption.
• Before the test, it is recommended to fast for 8–12 hours. Intense physical activity should be avoided before the test, as it can temporarily alter potassium concentration in the blood. Test results should be evaluated alongside other electrolytes and kidney function indicators.