1Vilniaus City Clinical Hospital, Vilnius, Lithuania
Potassium is the principal positive ion in the human body. Almost 98% of potassium is located in a cell, with the concentration gradient being supported by an adenosine triphosphatase pump (NA+ / K+ –ATPase). The ratio of the extracellular and intracellular potassium is important when trying to determine membrane potential of a cell. Potassium helps to preserve the balance of acidity and alkalinity, maintains isotonicity and cellular electrodynamic activity. Potassium also activates many enzyme-related reactions and plays an important role in transmitting nerve impulses, contracting heart, skeleton and smooth muscles, as well as supporting gastric secretion and kidneys. Hypokalemia is a condition when blood’s potassium levels drop below 3,5 mmol/l. It is one of the most frequently encountered electrolyte disorders in clinical practice, which can lead to many life-threatening complications. People with chronic heart and vascular disorders or kidney diseases are considered as high risk. A normal blood potassium level is 3,5 – 5,0 mmol/l. The severity of hypokalemia is normally classified by the serum potassium level: Light when serum potassium level is 3,0 – 3,4 mmol/l, moderate when serum potassium level is 2,5 – 3,0 mmol/l, and severe when serum potassium level drops below 2,5 mmol/l. Causes of hypokalemia include loss of potassium with urine or from digestive system, use of diuretics and adrenal hyperplasia. Symptoms are usually proportional to the severity and duration of hypokalemia. Usually, symptoms manifest when serum potassium level is lower than 3,0 mmol/l, except for instances when it drops suddenly, or a patient is susceptible to arrhythmia. The main cause of hypokalemia is determined after conducting a comprehensive anamnesis and appropriate physical tests. In order to determine severity of hypokalemia and prescribe an effective treatment it is crucial to evaluate potassium level in blood serum and urine. For patients with light or moderate hypokalemia, it is recommended to prescribe one-time intake of KCl. For patients with serum potassium levels below 2,5 mmol/l, intravenous correction of hypokalemia is recommended.
Keywords: hypokalaemia, potassium, electrolytes, kidneys, acid alkaline balance.