What is the reference range of chloride in serum?

• A. 90-100 mmol/L
• B. 96-108 mmol/L
• C. 110-120 mmol/L
• D. 80-90 mmol/L

Answer: (B)

Chloride is the major extracellular anion and helps maintain electroneutrality and osmotic balance, working with sodium and bicarbonate in acid–base regulation. The standard reference interval for serum chloride in healthy adults is 96 to 108 mmol/L. This range reflects typical physiological levels across populations and laboratory methods, so it’s the norm clinicians expect. Values above this range indicate hyperchloremia, while values below indicate hypochloremia, which can occur with dehydration, kidney issues, metabolic or respiratory disturbances, vomiting, or diuretic use. Since chloride is monovalent, mmol/L and mEq/L are effectively the same for this ion, so this interval is the commonly used reference.