What is a chloride blood test?

A chloride blood test measures the amount of chloride in your blood. Chloride is a type of electrolyte. Electrolytes are electrically charged minerals that help control the amount of fluids and the balance of acids and bases (pH balance) in your body. You have electrolytes in your blood, urine, tissues, and other body fluids.

You get chloride through the food you eat. It is mainly found in salt. Your body gets rid of the extra chloride in your urine (pee). Chloride helps control the amount of fluid in your body. In addition, it helps maintain healthy blood volume and blood pressure.

Many diseases and other factors can cause abnormal chloride levels. Chloride is often measured with other electrolytes to diagnose or monitor conditions such as kidney disease, heart failure, liver disease, and high blood pressure.

Other names: CI, Serum chloride

What is it used for?

You usually get a chloride test as part of a routine blood screening to check your general health. It's also used to help monitor or diagnose conditions related to an imbalance of acids or fluids in your body.

Why do I need a chloride blood test?

Your health care provider may have ordered a chloride blood test as part of an electrolyte panel, a routine blood test that measures chloride and other electrolytes, such as potassium, sodium, and bicarbonate.

You may also need a chloride blood test if you have symptoms of an acid or fluid imbalance, including:

• Vomiting over a long period of time
• Diarrhea
• Fatigue
• Weakness
• Dehydration
• Trouble breathing

What happens during a chloride blood test?

A health care professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. You may feel a little sting when the needle goes in or out. This usually takes less than five minutes.

Will I need to do anything to prepare for the test?

You may need to stop taking certain medicines before this test, so tell your provider about everything you take. But don't stop taking any medicines unless your provider tells you to.

If your provider has ordered other blood tests, you may need to fast (not eat or drink) for several hours before the test. Your provider will let you know if there are any special instructions.

Are there any risks to the test?

There is very little risk to having a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.

What do the results mean?

There are many reasons why your chloride levels may not be in the normal range.

High levels of chloride (hyperchloremia) may be a sign of:

• Dehydration.
• Kidney disease.
• Metabolic acidosis, a condition in which you have too much acid in your blood. It can cause nausea, vomiting, and fatigue.

Low levels of chloride (hypochloremia) may be a sign of:

• Heart failure.
• Lung disease.
• Addison disease, a condition in which your body's adrenal glands don't produce enough of certain types of hormones. It can cause various symptoms, including weakness, dizziness, weight loss, and dehydration.
• Metabolic alkalosis, a condition in which you have too much base in your blood. It can cause irritability, muscle twitching, and tingling in the fingers and toes.

If your chloride levels are not in the normal range, it doesn't always mean you have a medical problem that needs treatment. Many things can affect your chloride levels, such as drinking too much fluid or losing fluid because of vomiting or diarrhea. Also, certain medicines, such as antacids, can cause abnormal results. To learn what your results mean, talk with your provider.

Learn more about laboratory tests, reference ranges, and understanding results.

Is there anything else I need to know about a chloride blood test?

Urine also contains some chloride. Your provider may also recommend a urine chloride test to get more information about your chloride levels.