Illness and Conditions - Medical Tests
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 chloride.
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 urine.
Chloride can also be measured in skin sweat to test for cystic fibrosis .
Why It Is Done
A test for chloride may be done to:
How To Prepare
You do not need to do anything before you have this test.
Tell your doctor if you:
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:
The skin sweat test for chloride is primarily used to test for cystic fibrosis. For more information, see the medical test Sweat Test.
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 blood sample taken from a vein.
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.
High chloride levels may be caused by:
Low chloride levels may be caused by:
What Affects the Test
Reasons you may not be able to have the test or why the results may not be helpful include:
What To Think About
Last Revised: March 26, 2012
Fischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.
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