Chloride is an electrolyte. It is a negatively charged ion that works with other electrolytes, such as potassium, sodium, and bicarbonate, to help regulate the amount of fluid in the body and maintain the acid-base balance. This test measures the level of chloride in the blood and/or urine.
Chloride is present in all body fluids but is found in the highest concentration in the blood and in the fluid outside of the body's cells. Most of the time, chloride concentrations mirror those of sodium, increasing and decreasing for the same reasons and in direct relationship to sodium. When there is an acid-base imbalance, however, blood chloride levels can change independently of sodium levels as chloride acts as a buffer. It helps to maintain electrical neutrality at the cellular level by moving into or out of the cells as needed.
We get chloride in our diet through food and table salt, which is made up of sodium and chloride ions. Most of the chloride is absorbed by the digestive tract, and the excess is eliminated 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 test used?
A chloride blood test is used to detect an abnormal level of chloride. It is often used, along with other electrolytes, as part of a routine health exam to screen for a variety of conditions.
Chloride and other electrolyte tests may also be used to help diagnose the cause of signs and symptoms such as prolonged vomiting, diarrhea, weakness, and difficulty breathing (respiratory distress). If an electrolyte imbalance is detected, your healthcare practitioner will look for and address the disease, condition, or medication causing the imbalance and may use a series of electrolyte tests to monitor the effectiveness of treatment. If an acid-base imbalance is suspected, your healthcare practitioner may also order tests for blood gases to further evaluate the severity and cause of the imbalance.
Urine chloride tests may be used by your healthcare practitioner to determine whether the cause of alkalosis (too much base) is loss of salt (in cases of dehydration, vomiting, or use of diuretics, where urine chloride would be very low) or an excess of certain hormones such as cortisol or aldosterone that can affect electrolyte elimination.
When is it ordered?
The blood chloride test is almost never ordered by itself. It is usually ordered as part of an electrolyte panel, a basic metabolic panel, or a comprehensive metabolic panel, which are ordered frequently as part of a routine physical.
- Prolonged vomiting and/or diarrhea
- Weakness, fatigue
- Difficulty breathing (respiratory distress)
Electrolytes may be ordered at regular intervals when you have a disease or condition or are taking a medication that can cause an electrolyte imbalance. Electrolyte panels or basic metabolic panels are commonly ordered on a regular basis when you are being treated for certain conditions, including high blood pressure (hypertension), heart failure, or liver or kidney disease.
A urine chloride test may be performed along with a blood or urine sodium when evaluating the cause of low or high blood chloride levels. A healthcare practitioner will look at whether the chloride measurement changes mirror those of the sodium. This helps the healthcare practitioner determine if there is also an acid-base imbalance and helps to guide treatment.
What does the test result mean?
Chloride levels are typically interpreted along with results from other tests done at the same time, such as the results of other electrolyte tests. Low and high chloride levels can be caused by various conditions and diseases.
An increased level of blood chloride (called hyperchloremia) usually indicates dehydration, but can also occur with other problems that cause high blood sodium, such as Cushing syndrome or kidney disease. Increased blood chloride may also occur when too much base is lost from the body (producing metabolic acidosis) or when you hyperventilate (causing respiratory alkalosis).
A decreased level of blood chloride (called hypochloremia) may occur with any disorder that causes low blood sodium. Low chloride may also occur with congestive heart failure, diabetic ketoacidosis, aldosterone deficiency, prolonged vomiting or gastric suction, Addison disease, emphysema or other chronic lung diseases (causing respiratory acidosis), and with loss of acid from the body (called metabolic alkalosis).
An increased level of urine chloride can indicate dehydration, starvation, Addison disease, or consuming increased amounts of salt.
My chloride level is only slightly out of range. What does this mean?
Your chloride result is interpreted by your healthcare practitioner within the context of other tests that you have had done as well as other factors, such as your medical history. A single high or low result may or may not have medical significance. Generally, this is the case when the test value is only slightly higher or lower than the reference range. This is why healthcare practitioners may repeat a test on you and why they may look at results from prior times when you had the same test performed.
On the other hand, a result outside the range may indicate a problem and warrant further investigation. Your healthcare practitioner will evaluate your test results and determine whether a result that falls outside of the reference range means something significant for you.
Are there dietary recommendations for chloride?
Yes. The Food and Nutrition Board at the Institute of Medicine recommends that healthy adults ages 19 to 50 years consume 2.3 grams of chloride or 3.8 grams of salt per day. The recommendations vary based on age, sex, and other factors. These amounts replace what is lost on average each day through sweat. (For additional details, see the Food and Nutrition Board’s Dietary Reference Intakes.) Chloride is readily available in the food supply and most Americans probably consume more than necessary, in the form of table salt and salt in prepared foods. It is also found in many vegetables and in foods such as salted meats, butter, tomatoes, lettuce, celery, and olives.
What treatment is prescribed for abnormal chloride levels?
Is there anything else I should know?
Drugs that affect sodium blood levels will also cause changes in chloride. In addition, swallowing large amounts of baking soda or substantially more than the recommended dosage of antacids can also cause low blood chloride.