Chloride is an essential electrolyte in your body. It's a major extracellular anion whose role is to maintain normal blood volume and osmotic pressure. It works closely with other electrolytes like sodium, potassium, and bicarbonate to maintain the acid-base balance of your blood. 

Chloride is best known as one of the ingredients of table salt. Once ingested, it is absorbed by the intestinal tract. Excessive amounts are eliminated from the body through urine, stool, and sweat. 

Hyperchloremia or increased levels of chloride usually indicate dehydration or kidney disease. This condition can be caused by an extremely high dietary intake of salt. High chloride levels are connected to metabolic acidosis, meaning the amount of bicarbonate in the blood decreases, and your blood is too acid (this means that the pH of your blood is lower than expected). When a person hyperventilates and breathes excessively, respiratory alkalosis can occur, which can cause chloride levels to rise. Hyperchloremia can also be caused by kidney disease or Cushing's syndrome. 

You typically ingest chloride through salt in your food; therefore, it is very rare to be nutritionally deficient in chloride. Hypochloremia or low chloride levels can occur due to severe and prolonged vomiting, diarrhea, or excessive sweating. However, overhydration or any condition that increases the volume of your extracellular fluid can cause low chloride levels as well. Metabolic alkalosis is a condition where the amount of bicarbonate in the blood is increased (this means that the pH of your blood is higher than expected) and can cause the level of chloride to drop. On the other hand, chronic respiratory acidosis is a condition when your body cannot remove carbon dioxide from the body, which can cause the level of chloride to drop. Hypochloremia can also be caused by Addison's disease, lung disease, congestive heart failure, or certain medications.