What Is a Blood Chloride Test?

A Basic Laboratory Test Used to Help Diagnose Many Medical Conditions

A blood chloride test is a common diagnostic test used in many different medical settings. It is usually given and interpreted along with other tests, such as those for other electrolytes.

Purpose of Test

To understand why you might need a blood chloride test, it’s helpful to understand what the test measures.

Chloride is a type of electrolyte. These are substances of very small size, called ions, that carry either a positive or a negative kind of charge. Different electrolytes are found in varying concentrations at different places inside your body, such as inside your blood or in the fluid in your cells.

A blood chloride test measures the concentration of chloride ions in your blood. Having levels that are too high or too low can be a sign of many potential health conditions.

Chloride ion has a negative charge, and it is notated as CL-. Some other key electrolytes are:

  • Sodium ions (Na+)
  • Potassium ions (K+)
  • Bicarbonate ions (HCO3- )

These electrolytes work together synergistically, in that the concentration of one sometimes affects the concentration of another. Also, medical conditions that affect one of these electrolytes often affect the others as well.

Because of this, a blood chloride test is rarely performed on its own. Instead, it is usually done as part of something called an electrolyte panel, which also includes sodium, potassium, and bicarbonate ions. Or it might be included with a larger group of blood tests, called a basic metabolic panel (BMP).

In addition to the above, it also includes glucose, calcium, and tests of kidney function. It may also be included as part of a comprehensive metabolic panel (CMP), which includes additional tests.

Why Might You Need a Blood Test for Electrolytes?

Having the right electrolytes in the right places is extremely important for many aspects of your health. They play critical roles in metabolism, activation of enzymes, and in muscular and nervous system signaling. They also play an important role in acid/base balance, which affects the acidity of your blood and other tissues.

This is critical since the blood needs to be maintained within a relatively small window of acidity values (called pH). If not, it can be both a cause and a sign of health problems that potentially might be life-threatening.

Because electrolytes (including chloride) are so important for so many different processes in your body, you might have your electrolytes checked as part of many different basic screening tests.

You also might need to be tested regularly if you take a medication that can affect electrolyte levels, like certain medications for kidney or heart disease.

Electrolytes are also a key diagnostic aid for people who have many different types of symptoms. For example, you might have blood drawn for such a test if you have any of the following symptoms:

  • Extreme vomiting
  • Signs of dehydration
  • Diarrhea
  • Body swelling
  • Difficulty breathing

People who are seriously ill, such as those staying in the intensive care unit, are also likely to need repeated checks of their electrolytes.

Risks and Contraindications

This test is performed via a simple blood draw, and there are no major risks involved. You might have some slight pain or bleeding at the blood draw site. Sometimes people feel a little light-headed.

Let your clinician know if you have any conditions that increase your risk of bleeding, like certain genetic conditions. Also make sure they are aware of any medications that you take that might increase bleeding, like Coumadin (warfarin)

Before the Test

No test preparation is needed before getting a chloride test as part of an electrolyte panel. If you are having it done at the same time as certain other tests, you might need to fast before having your blood drawn.

You might want to wear a loose-fitting shirt, so it’s easy for the phlebotomist to assess a vein on your upper arm. The test might be performed at a hospital or in an outpatient setting. Usually, the process only takes a few minutes.

During the Test

To perform the test, a health care professional needs to take a blood sample. Someone will clean the area. Next, a tourniquet will be applied above the area of the vein to be used, usually the upper arm. You may be asked to squeeze your fist while your phlebotomist finds a good vein to use.

The needle will be inserted into a vein in your arm. This usually only hurts for a moment or two.

The blood sample can be used to perform many types of analysis (such as for a BMP), but you’ll only need to be stuck once.

After the Test

The sample is promptly sent to a medical laboratory for analysis. In almost all cases, you will be able to return to your normal activities right away.

If you are dizzy after the blood draw, you may need to sit for a while or have something to eat or drink before going about the rest of your day. You might have some soreness or bruising where your blood was taken.

Interpreting Results

A blood chloride test is not diagnostic for any single medical condition. Instead, abnormalities can be one indicator related to a lot of different types of problems. But, used in combination with your medical history, exam, and other tests, it can help play a role in diagnosis.

It’s especially important that health professionals interpret the chloride test in the context of other electrolytes.

Normal Levels of Blood Chloride

Hyperchloremia refers to blood chloride levels that are higher than the normal range. On the other hand, hypochloremia describes blood chloride levels that are lower than normal. Either of these can indicate a medical problem.

Depending on the context, results might be available within a couple of hours or in a day or two. These results will indicate whether your blood showed hyperchloremia, hypochloremia, or normal concentrations of chloride.

The reference ranges for these conditions may vary depending on the specific type of laboratory analysis done and on other factors.

Historically, the National Institute of Health has considered hypochloremia to be less than 99 mmol/L. Hyperchloremia has been considered greater than 107 mmol/L.

Hyperchloremia

Hyperchloremia can arise from many different causes. These include:

  • Dehydration from fever, perspiration, or inadequate water intake
  • Certain kinds of diarrhea
  • Certain kidney problems
  • Diabetes insipidus
  • Saltwater drowning
  • Severe burns
  • Cushing syndrome
  • Certain medical problems causing a person to breathe quickly

Sometimes patients in the intensive care unit get hyperchloremia from all of the intravenous fluids they have been given. (For example, they might need a lot of fluids because of sepsis, an overwhelming response to infection.) These fluids contain chloride ions, along with other electrolytes. Though these fluids are often life-saving, it is not uncommon for the concentration of chloride to become abnormal.

Hypochloremia

Hypochloremia can also be caused by many different things. These include:

  • Vomiting
  • Congestive heart failure
  • SIADH (syndrome of inappropriate ADH secretion)
  • Medical conditions causing reduced breathing rate (like emphysema)
  • Addison’s disease
  • Therapy with certain diuretic drugs (like for blood pressure)
  • Taking larger than recommended doses of antacids

Follow-Up

Much of the time, an abnormal chloride test is a sign of a problem that needs to be addressed in the context of your full medical picture. Lab errors do occur occasionally though.

If you have an abnormal chloride blood test, you will probably need the test repeated to see if it comes back to normal. Your medical team may need to perform additional diagnostic tests, such as imaging and other lab tests, to figure out what is going on. Or you might need a follow-up electrolyte test if your clinician thinks your abnormal blood chloride is due to a medication.

Depending on the situation, your health care provider might have you get a urine chloride test if the results of your blood chloride were abnormal. This can give additional diagnostic information if it’s needed.

Don’t confuse a blood chloride test with something called a “sweat chloride test.” The latter is a test sometimes performed to help diagnose the genetic condition cystic fibrosis. The blood chloride test is not used for this.

A Word From Verywell

Blood chloride is helpful basic laboratory test performed in many different medical circumstances. In most cases, you’ll get your blood chloride checked along with other basic laboratory tests. It can be concerning to have an unexpected lab result, but it’s best not to get fixated on a single abnormal number. Instead, work with your healthcare provider to interpret your results in the context of your full medical story. 

Was this page helpful?

Article Sources

  1. Arneson W. Electrolytes: the salts of the earth. Laboratory Medicine. 2014;45(1):e11–e15. doi:10.1309/LM24GWIUEXOKN7AP

  2. American Association for Clinical Chemistry. Basic metabolic panel. Reviewed December 2, 2015. 

  3. American Association for Clinical Chemistry. Electrolytes. Reviewed December 2, 2015. 

  4. Yunos NM, Bellomo R, Story D, Kellum J. Bench-to-bedside review: Chloride in critical illnessCrit Care. 2010;14(4):226. doi:10.1186/cc9052

  5. Nagami GT. Hyperchloremia—why and how. Nefrologia. 2016;36(4):347-53. doi:10.1016/j.nefro.2016.04.001

  6. American Association for Clinical Chemistry. Chloride. Reviewed January 26, 2016.

Additional Reading