A chloride test measures the level of chloride
in your blood or urine. Chloride is one of the most important
electrolytes in the blood. It helps keep the amount of
fluid inside and outside of your cells in balance. It also helps maintain
proper blood volume, blood pressure, and
pH of your body fluids. Tests for sodium, potassium,
and bicarbonate are usually done at the same time as a blood test for
Most of the chloride in your body comes from the salt
(sodium chloride) you eat. Chloride is absorbed by your
intestines when you digest food. Extra chloride leaves
your body in your urine.
Sometimes a test for chloride can be done
on a sample of all your urine collected over a 24-hour period (called a 24-hour
urine sample) to find out how much chloride is leaving your body in your
Help find the
cause for high blood pH. A condition called metabolic alkalosis can be caused
by a loss of acid from your body (for example, from a loss of electrolytes
through prolonged vomiting or diarrhea). You may also have metabolic alkalosis
if your body loses too much sodium or you eat too much baking soda (sodium
How To Prepare
You do not need to do anything before
you have this test.
bleeding problems or take blood-thinners, such as aspirin or warfarin
Are or might be pregnant.
Talk to your doctor about any concerns you have regarding
the need for the test, its risks, how it will be done, or what the results will
mean. To help you understand the importance of this test, fill out the
medical test information form(What is a PDF document?).
How It Is Done
The health professional taking a sample
of your blood will:
Wrap an elastic band around your upper arm to
stop the flow of blood. This makes the veins below the band larger so it is
easier to put a needle into the vein.
Clean the needle site with
Put the needle into the vein. More than one needle stick
may be needed.
Attach a tube to the needle to fill it with
Remove the band from your arm when enough blood is
Put a gauze pad or cotton ball over the needle site as
the needle is removed.
Put pressure on the site and then put on a
You start collecting your urine in the
morning. When you first get up, empty your bladder but do not save this urine.
Write down the time that you urinated to mark the beginning of your 24-hour
For the next 24 hours, collect all your urine.
Your doctor or lab will usually provide you with a large container that holds
about 1 gal (4 L). The
container has a small amount of preservative in it. Urinate into a small, clean
container and then pour the urine into the large container. Do not touch the
inside of the container with your fingers.
Keep the large container
in the refrigerator for the 24 hours.
Empty your bladder for the
final time at or just before the end of the 24-hour period. Add this urine to
the large container and record the time.
Do not get toilet paper,
pubic hair, stool (feces), menstrual blood, or other foreign matter in the
The skin sweat test for chloride is primarily used to
test for cystic fibrosis. To learn more, see the topic
How It Feels
The blood sample is taken from a vein
in your arm. An elastic band is wrapped around your upper arm. It may feel
tight. You may feel nothing at all from the needle, or you may feel a quick
sting or pinch.
There is no pain while collecting a
24-hour urine sample.
There is very little chance of a
problem from having a blood sample taken from a vein.
You may get a small bruise at the site. You
can lower the chance of bruising by keeping pressure on the site for several
In rare cases, the vein may become swollen after the blood
sample is taken. This problem is called phlebitis. A warm compress can be used
several times a day to treat this.
Ongoing bleeding can be a problem for people with bleeding
disorders. Aspirin, warfarin (Coumadin), and other blood-thinning medicines can
make bleeding more likely. If you have bleeding or clotting problems, or if you
take blood-thinning medicine, tell your doctor before your blood sample is
There is no chance for problems while
collecting a 24-hour urine sample.
A chloride test measures the level of
chloride in your blood or urine. Chloride is one of the most important
electrolytes in the blood, along with sodium,
potassium, and calcium. Chloride helps keep the amount of fluid inside and
outside of your cells in balance.
The normal values listed here—called a reference range—are just a guide. These ranges vary from lab to lab, and your lab may have a different range for what's normal. Your lab report should contain the range your lab uses. Also, your doctor will evaluate your results based on your health and other factors. This means that a value that falls outside the normal values listed here may still be normal for you or your lab. Blood chloride levels are checked more often than urine chloride levels.
Results are usually available in 1 to 2 days.
Failing to collect exactly 24
hours of urine during a 24-hour urine test for chloride.
What To Think About
The results from a blood or urine chloride test
do not provide enough information to diagnose a specific disease or problem.
Your doctor will talk with you about how your results may be caused by your
symptoms or past health.
Potassium chloride (found in salt
substitutes) can lower your blood chloride levels but raise your urine chloride
Tests for sodium, potassium, and bicarbonate usually are
done at the same time as a blood test for chloride.
How this information was developed to help you make better health decisions.