Hyperkalemia is a medical condition characterized by an abnormally high level of potassium in the bloodstream, typically defined as a serum potassium concentration greater than 5.0 milliequivalents per liter (mEq/L). It can result from various factors, including kidney dysfunction, certain medications, or excessive potassium intake. Symptoms may include muscle weakness, fatigue, and heart rhythm disturbances, making it a potentially serious condition that requires prompt medical attention. Treatment often involves addressing the underlying cause and may include medications, dietary changes, or procedures to lower potassium levels.