Chloride
Chloride is a salt mineral in your blood. It works with sodium to balance fluids and acid, and it is part of the basic and comprehensive metabolic panels.
AI-verified against cited sources. Awaiting expert reviewAlso called Cl, Cl-LOINC 2075-0
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What it is
Chloride is the main negatively charged mineral (electrolyte) in the fluid outside your cells. Most of it comes from the salt in food. It works with sodium to keep water in the right places, and it helps keep your blood's acid balance steady. Your kidneys adjust how much chloride you keep or lose each day.
Why it matters
Chloride usually moves up and down with sodium, so clinicians read it together with sodium, potassium and bicarbonate. On its own, a result slightly outside the range often means little. The pattern across these tests, and the anion gap worked out from them, helps show what is going on with your fluids and acid-base balance.
If it’s low
A result below your lab's range is called low chloride (hypochloremia). It often goes along with low sodium and extra body water, or with losing stomach acid and fluid through vomiting. Water pills (diuretics) can also lower it. Mild changes are common, and your clinician can put your result in context.
Common causes
- Vomiting or stomach suction, which removes chloride-rich stomach acid
- Too much body water or fluid overload, such as with heart failure
- Water pills (diuretics)
- Conditions that raise bicarbonate (metabolic alkalosis), or long-term lung disease that holds on to carbon dioxide
- Addison disease or other conditions that make the body lose salt
- A falsely low result when blood has very high fat (triglyceride) or protein levels, on some lab methods
What can help
- Ask your clinician whether vomiting, fluid balance or a medicine could explain it
- Ask whether sodium, potassium and bicarbonate should be checked along with it
- Ask your clinician before changing how much salt or fluid you take
If it’s high
A result above your lab's range is called high chloride (hyperchloremia). It is often linked to dehydration, or to receiving a lot of salt-containing fluid through a drip. It can also go along with more acidic blood when the body loses bicarbonate, as with diarrhea or some kidney problems. Mild changes are common, and your clinician can put your result in context.
Common causes
- Dehydration
- Large amounts of salt-containing IV fluid (normal saline)
- Diarrhea or other loss of bicarbonate, which lets chloride rise to balance it
- Kidney conditions that make it harder to remove acid, such as renal tubular acidosis
- Some medicines or supplements that add chloride or cause bicarbonate loss
- A falsely high result from bromide in some medicines or exposures, on some lab methods
What can help
- Ask your clinician whether you may be dehydrated or have recently had IV fluids
- Ask whether bicarbonate, sodium and kidney function should be reviewed together with chloride
- Tell your clinician about all medicines and supplements you take, including anything that contains bromide
Usual ranges
What labs print as the reference range, by who was tested. Ranges differ a little between labs, so the range on your own report is the one your result is judged against.
For adults: 96–106 mmol/L. Source: Labcorp, Mayo Clinic Laboratories.
- Adults (this one applies)96–106 mmol/L
Sources: Labcorp, Mayo Clinic Laboratories
See Chloride by age and sex, with the U.S. survey numbers where they exist.
How common is your level?
NHANES describes the US civilian, non-institutionalized population, not a 'healthy' reference group. People with disease, on medication, fasting or not (except fasting-subsample markers), smokers and so on are all included. A percentile says where a value sits among Americans of that sex and age, not whether it is normal.
Use the left and right arrow keys to read each age. Shift moves five years.
Reference data derived from CDC/NCHS National Health and Nutrition Examination Survey (NHANES), cycles August 2021-August 2023. Analysis by bloodtesttracker.com; not endorsed by CDC, NCHS or HHS.
Explore Chloride by age and sex: every percentile as a table, with a download.
What can affect your result
- Fluid balance: dehydration or extra body water
- Vomiting, diarrhea and sweating
- Medicines, especially water pills (diuretics)
- Kidney, lung and heart conditions
- Age: some labs list different ranges for children and adults
- Lab method: bromide can falsely raise chloride, and very high fat or protein levels can falsely lower it on some methods
- Bromide (found in some medicines and chemicals) can make chloride read falsely high on ion-selective electrode methods, and can produce a negative anion gap.
- Very high triglycerides or protein levels can make chloride read falsely low on indirect ion-selective electrode methods.
- Badly hemolyzed samples can be rejected (Mayo Clinic Laboratories).
Chloride follows fluid and acid-base shifts, so it can change within hours to days.
When to talk to a clinician
Contact the clinician who ordered the test soon if your result is outside your lab's range and you also have repeated vomiting or diarrhea, marked weakness, confusion, very little urine or swelling. If your lab or clinician has flagged the result as urgent, call the clinician who ordered the test today. Call 911 or your local emergency number for chest pain, fainting, a seizure or severe confusion.
Questions you could ask
- Do any of my medicines or supplements affect my electrolytes?
- How often should we recheck my electrolytes?
- Could dehydration or IV fluids explain a higher chloride?
- Should we look at my bicarbonate, sodium and anion gap together?
- Could vomiting, fluid balance or one of my medicines explain a lower chloride?
- Should we check my sodium, potassium and bicarbonate too?
Questions people ask
Why do I get a chloride test if it is rarely the problem?
Chloride is part of the basic and comprehensive panels because it helps your clinician read your sodium and bicarbonate, and it is used to work out the anion gap. A mild change on its own often means little, but the pattern across your electrolytes can show what is going on with fluids and acid balance.
Does my chloride level show how much salt I eat?
Not usually. Your kidneys adjust to keep the blood level steady, so it tends to reflect fluid and acid-base balance more than your diet. Talk with your clinician before changing how much salt you eat.
Why do labs show different ranges, like 96–106 and 98–107?
Each lab sets its own range using its own method and patients. Labcorp lists 96–106 mmol/L, and Mayo Clinic Laboratories lists 98–107 mmol/L for adults. Use the range printed on your own report first.
Is mEq/L the same as mmol/L for chloride?
Yes. Chloride carries a single charge, so the numbers are the same in both units. A result of 100 mmol/L is 100 mEq/L.
What is the anion gap, and how does chloride fit in?
The anion gap is sodium minus the sum of chloride and bicarbonate. Many labs calculate it from your electrolyte panel. Clinicians use it to help sort out the causes of acid-base changes.
Show the science and sources
Units
- 1 mmol/L = 1 mmol/L
- 1 mmol/L = 1 mEq/L
Is a change real?
Chloride naturally varies about 1.1% from test to test in the same healthy person. Between two results from the same lab, a change of roughly 3% or more is unlikely to be day-to-day noise or lab variation (95% reference change value). Source: Critical appraisal and meta-analysis of biological variation estimates for kidney related analytes (Jonker N et al., EFLM WG-BV).
For clinicians and researchers
Chloride is the major extracellular anion, and serum levels generally move with sodium. Most filtered chloride is reabsorbed by the kidney, about 60% in the proximal tubule. Labs measure it with ion-selective electrodes, usually indirect ISE on high-throughput analyzers. Indirect ISE is affected by the electrolyte exclusion effect, so severe hypertriglyceridemia or paraproteinemia can cause pseudohypochloremia, while direct ISE is not affected. Bromide reacts with most chloride reagents more strongly than chloride does, so bromism can cause pseudohyperchloremia with a negative anion gap (in one case report, results reached 175 mmol/L and higher, and a same-sample comparison gave 135 mmol/L by indirect ISE versus 103 mmol/L by a colorimetric chloridometer). Low chloride with normal sodium and high bicarbonate suggests chloride depletion, as with loop diuretics, while low chloride with low sodium suggests dilution. Hyperchloremic (normal anion gap) metabolic acidosis results from gastrointestinal or renal bicarbonate loss. Hypochloremia is often defined as below 96 mmol/L and hyperchloremia as above 105 to 115 mmol/L, depending on the lab. Reference intervals differ: Labcorp 96–106 mmol/L for all ages, Mayo Clinic Laboratories 98–107 for adults and 102–112 for ages 1 to 17. ARUP and Quest do not publish a chloride critical limit, and hospital critical-value lists differ (Houston Methodist 75 or lower and 121 or higher, Michigan Medicine Laboratories below 80 or above 130 mmol/L), so no critical limit is set here.
LOINC 2075-0 (primary), 2069-3. Specimen: serum-or-plasma.
Sources
- Chloride (test 001206), Labcorp
- Chloride, Serum (test ID CL), Mayo Clinic Laboratories
AI-verified against cited sources. Awaiting expert review. Last reviewed 2026-10-03. How we build and check these pages.