Synonyms
Hypokalemia, potassium deficiencyPotassium is an electrolyte (bulk element) that is important above all for the excitability of muscle and nerve cells and for fluid and hormone balance. It must be supplied to the body regularly from outside, as a small amount is excreted every day. Potassium is found in large quantities in meat, fruit (bananas, apricots, figs etc.
), nuts and vegetables (potatoes). Electrolytes are distributed throughout the body in different rooms after absorption through food. These are mainly the blood on the one hand and the cell interiors and cell spaces on the other.
99% of all potassium in the body is found in the cell interiors. Consequently, the concentration of potassium is very high (~150 mmol/l, not directly determinable) in the cell interiors and very low (~4 mmol/l, determinable by blood sampling) in the blood. This difference in concentration must be maintained, as it is decisive for the excitability of body cells (especially muscle/neuron cells). In the short term, fluctuations in the blood concentration (e.g. due to food intake) are compensated by the further transfer of potassium to the inside of cells; in the long term, the kidneys excrete the potassium via urine in a way that varies from person to person. If the kidney function is insufficient, the large intestine can increasingly take over this task, which in healthy individuals plays a subordinate role in potassium excretion.
Definition
The normal blood potassium concentration is 3.6 – 5.4 mmol/l. A concentration below 3.5 mmol/l is called potassium deficiency (hypokalemia), below 3.2 mmol/l this is usually manifested by physical symptoms and below 2.5 mmol/l the potassium deficiency can be considered life-threatening.
Occurrence
The potassium concentration in the blood is susceptible to fluctuations because the amount of potassium and the tolerance range are relatively small. It is a considerable achievement of the body to keep the concentration in the blood constant despite the fluctuations in food intake. Accordingly, potassium deficiency is a common electrolyte disorder. The frequency is about 2-6% of in-patients in hospital, mostly due to dehydrating medication (diuretics). The majority is mild.
