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:
- Check your chloride level if you are having symptoms such as muscle twitching or spasms, breathing problems, weakness, or confusion.
- Find out whether you have kidney or adrenal gland problems.
- 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 bicarbonate).
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?).