Hypokalemia refers to a condition where blood potassium levels are below 3.5mmol/L. The causes can be due to inadequate intake of potassium, such as prolonged inability to eat without sufficient intravenous supplementation of potassium. It can also result from excessive loss of potassium, through external losses such as vomiting and diarrhea, or through renal losses due to the excessive use of diuretics and certain hormonal imbalances. A third cause involves the shift of potassium into cells, such as during episodes of alkalemia and periodic paralysis. Clinically, mild to moderate hypokalemia is characterized by symptoms like muscle weakness, fatigue, cramps, intestinal obstruction, and some abnormalities in electrocardiograms, including the presence of U waves and flattened T waves. Severe hypokalemia can lead to life-threatening arrhythmias, such as ventricular tachycardia and ventricular fibrillation, which require immediate treatment.