At a glance

Also known as

Cl

Why get tested?

To determine if there is a problem with your body’s acid-alkali (pH) balance and to monitor treatment

When to get tested?

If your doctor thinks that you have an electrolyte imbalance

Sample required?

A blood sample drawn from a vein in the arm, or a urine sample

Test preparation needed?

None

What is being tested?

Chloride is an electrolyte. When combined with sodium it is mostly found in nature as ‘salt.’ Chloride is important in maintaining the normal acid-base balance of the body and, along with sodium, in keeping normal levels of water in the body. Chloride generally increases or decreases in direct relationship to sodium, but may change without any change in sodium when there are problems with too much acid or base in your body. Chloride is taken into the body through food. Most of the chloride is absorbed by the gastrointestinal tract, and the excess is excreted in urine. The normal blood level remains steady, with a slight drop after meals (because the stomach produces acid after eating, using chloride from blood).

How is the sample collected for testing?

A blood sample is taken by needle from the arm. Chloride can also be measured in a urine sample.

The Test

How is it used?

Blood chloride may be useful along with sodium, to evaluate problems with the acid-base balance in the body, and to monitor treatment.

When is it requested?

A blood chloride test may be requested to help evaluate kidney function and acid-base status. If your sodium measurement is abnormal, your doctor may look at whether the chloride measurement changes in the same way. This may help your doctor to work out if there is also a problem with acid or base and may help guide treatment.

What does the test result mean?

Looking for reference ranges?

A severe elevation or loss of this electrolyte can indicate a serious fluid and electrolyte imbalance. The type of medical treatment depends on the cause of the problem.

Increased levels of chloride (called hyperchloraemia) usually indicate dehydration, but can also occur with any other problem that causes high blood sodium. Hyperchloraemia also occurs when too much alkaline fluid is lost from the body (producing metabolic acidosis), or when a person hyperventilates (causing respiratory alkalosis).

Decreased levels of chloride (called hypochloraemia) occur with any disorder that causes low blood sodium. Hypochloraemia also occurs with prolonged vomiting or gastric suction, emphysema or other chronic lung disease (causing respiratory acidosis), and with loss of alkaline fluid from the body (called metabolic alkalosis).

Common Questions

Where does chloride come from in the diet?

Most chloride is attached to sodium in the form of sodium chloride, or table salt.

What treatment is prescribed to affect chloride levels?

The same treatment used to treat sodium imbalances - diuretics, fluid replacement, etc - may be used to treat chloride imbalance.