Chloride
What this test measures
Chloride is a salt that travels with sodium in the fluid outside the cells and helps keep the body's acid balance and fluid volume steady. It usually rises and falls in step with sodium. The test measures its concentration in a blood sample.
Why doctors request it
It is printed as part of some U&E panels and is mainly used by doctors, together with bicarbonate, to work out why the body's acid balance has changed or to calculate the anion gap.
What commonly pushes it up
- Dehydration
- Large volumes of saline drip
- Diarrhoea, where bicarbonate is lost
- Some kidney conditions and some medicines such as acetazolamide
What commonly pushes it down
- Vomiting, which loses stomach acid
- Water tablets
- Drinking a very large amount of water
- Chest conditions where carbon dioxide builds up
- Heart failure with fluid build-up
Everyday reasons for a value outside the range
- It tracks sodium, so anything that shifts sodium (hydration, drips) shifts chloride too
- Some labs print a narrower range than others
- Bromide-containing medicines can make it read falsely high
About the sample
No fasting needed. Usually interpreted together with sodium and bicarbonate rather than alone.
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Read my report freeThis is an educational summary of results you uploaded. It is not medical advice, a diagnosis or a treatment plan, and it does not replace the doctor who requested the test. If you are worried, or a result is marked outside range, discuss it with your doctor. Written and reviewed by a UK consultant physician. Reference ranges vary between laboratories.