Chloride is an essential electrolyte that plays a key role in maintaining fluid balance and regulating acid-base levels in the body. The chloride test, also known as the serum chloride level, is typically included in a comprehensive metabolic panel (CMP) or basic metabolic panel (BMP). These panels also measure other vital electrolytes, such as sodium, potassium, and carbon dioxide. Maintaining the proper balance of these electrolytes is crucial for the normal functioning of muscles, heart, and nerves, as well as for proper fluid absorption and excretion.