Hüpokalemia

Hüpokalemia, commonly known in English as hypokalemia, is a medical condition defined by a lower than normal concentration of potassium in the blood. Potassium is a key electrolyte involved in muscle function, nerve signaling, and cardiac conduction. Normal serum potassium is about 3.5 to 5.0 mEq/L; hüpokalemia is typically considered present when levels fall below 3.5 mEq/L.

Causes of hüpokalemia are diverse and often relate to losses or shifts of potassium. Common renal causes include use of loop or thiazide diuretics, primary or secondary hyperaldosteronism, and certain inherited tubulopathies such as Gitelman or Bartter syndrome. Gastrointestinal losses from vomiting, diarrhea, or laxative abuse can deplete potassium. Potassium may also move from the extracellular to the intracellular space during alkalosis, with insulin excess, or after substantial catecholamine stimulation. Inadequary intake alone is uncommon to cause marked decline but can contribute in poor nutritional states.

Symptoms range from mild to severe and may include muscle weakness, cramping, fatigue, and constipation; in more serious cases there can be arrhythmias or paralysis. ECG findings often show flattened or inverted T waves, the appearance of U waves, and sometimes QT prolongation.

Diagnosis relies on a blood test measuring serum potassium, with evaluation of kidney function, acid–base status, and urinary potassium to distinguish renal from non-renal losses. The total body potassium may be depleted even if serum levels are near the lower limit of normal.

Treatment depends on severity and symptoms. Mild cases are managed with oral potassium supplementation and addressing the underlying cause. Moderate to severe hüpokalemia or symptomatic cases require careful potassium replacement, often intravenously with cardiac monitoring. Potassium repletion must be gradual and tailored to renal function to avoid hyperkalemia, particularly in patients with kidney disease or ongoing tissue breakdown.