Hypokalemia, which is low potassium levels in the blood, can occur due to various reasons. Some common causes include excessive vomiting or diarrhea leading to potassium loss, certain medications such as diuretics, kidney disorders impairing potassium reabsorption, and hormonal imbalances such as excess aldosterone secretion. Hypokalemia can result in muscle weakness, abnormal heart rhythms, and other symptoms.