High potassium levels, known as hyperkalemia, occur when there is an excess of potassium in the bloodstream. Potassium is an essential mineral that helps regulate heart function, muscle contractions, and nerve signals. Normal potassium levels typically range from 3.5 to 5.0 milliequivalents per liter (mEq/L). When levels exceed this range, it can lead to serious health issues. Causes of high potassium levels include kidney dysfunction, certain medications, and excessive potassium intake from foods or supplements. Symptoms may include muscle weakness, fatigue, and irregular heartbeats. If left untreated, hyperkalemia can result in severe complications, including cardiac arrest.