Serum chloride refers to the concentration of chloride ions in the serum. chloride is the main anion in the human extracellular fluid and plays an important role in regulating the acid-base balance, osmotic pressure and water distribution in the human body. The normal value of blood chloride is 96-106 mmol/L. Common causes of increased blood chloride are: i. Decreased chloride excretion from the body, such as obstruction of the urinary tract, acute glomerulonephritis in anurics, and decreased renal blood flow (e.g., hemorrhagic heart failure). Second, excessive chloride intake, such as a long-term high-salt diet, or excessive input of chlorine-containing fluids. III. Respiratory alkalosis due to hyperventilation syndrome. IV. In hypernatremic dehydration, an increase in blood chloride is also seen.