Chloride blood test: normal range explained

Chloride is an electrolyte, a mineral with an electric charge that helps regulate the amount of fluid in your body and its acid-base (pH) balance. Most of it comes from the salt in food, and the kidneys remove the extra in urine. Together with sodium it helps control fluid volume, blood volume and blood pressure.

The test is usually part of an electrolyte panel, which also measures sodium, potassium and bicarbonate, or of a kidney or metabolic panel.

Doctors include chloride in routine screening and use it with the other electrolytes to help diagnose or monitor kidney disease, heart failure, liver disease and high blood pressure. It may also be ordered for symptoms of a fluid or acid imbalance, such as long spells of vomiting or diarrhoea, weakness, dehydration or trouble breathing.

When sodium is abnormal, a doctor checks whether chloride has moved the same way, because the pair helps show whether an acid-base problem is also present.

Chloride tends to follow sodium and fluid, so the things that change your hydration change the result too.

• Dehydration can raise chloride, while drinking very large amounts of fluid can lower it.
• Long spells of vomiting, stomach suction or chronic diarrhoea can lower chloride.
• Medicines that change sodium, such as diuretics, change chloride as well, and heavy antacid or laxative use can lower it. Do not stop a medicine unless your doctor tells you to.
• Breathing patterns matter: hyperventilation is linked with a higher chloride, and chronic lung disease such as emphysema with a lower one.
• Kidney disease is linked with a higher chloride, and adrenal gland disorders can shift it in either direction.
• Carbonic anhydrase inhibitors, a type of glaucoma medicine, can raise chloride.