Urine Chloride, Random
Chloride in one urine sample. Clinicians mainly use it to help work out why blood bicarbonate is high. It is not a routine test.
AI-drafted. Awaiting verificationAlso called UCl, U-ClLOINC 2078-4
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What it is
Chloride is a salt mineral that travels with sodium in the body. Your kidneys remove extra chloride in urine, so the amount in urine changes with how much salt you eat, how much fluid your body holds, and some medicines. A random urine chloride is a quick snapshot of that. It is most often used to help sort out the cause when the blood has become too alkaline.
Why it matters
When blood bicarbonate is high, urine chloride helps separate two broad groups of causes. A low value (under about 20 mmol/L) is typical when the body is short of fluid and chloride, for example after vomiting. A higher value is typical when other things are going on, such as hormone effects on the kidney, or when water pills are still working. Because the number follows what you eat and drink, clinicians read it together with blood tests, blood pressure and your history.
If it’s low
A low value (under about 20 mmol/L) means little chloride is leaving in your urine. This often happens when the body is holding on to salt and water, such as after vomiting or other fluid loss, with a low-salt diet, or after water pills have worn off. If your blood bicarbonate is high, it points clinicians toward causes linked to fluid or chloride loss.
Common causes
- Vomiting or stomach drainage
- Low salt intake
- Water pills (diuretics) after their effect has worn off
- Dehydration or other fluid loss
What can help
- Ask what may be causing the fluid or chloride loss
- Ask whether a recent diuretic could have affected the result
If it’s high
A higher value means more chloride is leaving in your urine. That is common with a salty diet, recent IV fluids, or while water pills are working. If your blood bicarbonate is high, a value above about 20 mmol/L points clinicians toward different possible causes than a low value does. It does not name a cause by itself.
Common causes
- High salt intake
- Diuretics (water pills) that are currently working
- Recent IV fluids that contain salt
- Conditions that affect the hormones controlling salt and potassium, which a clinician may look for when bicarbonate is high and potassium is low
What can help
- Ask your clinician how this result fits with your blood bicarbonate, potassium and blood pressure
- Tell your clinician about any diuretics or other medicines you take, since they change this test
What can affect your result
- Salt intake
- Diuretics: urine chloride is high while they work and low after they wear off
- Vomiting, diarrhea or other fluid loss
- Recent IV fluids
- How concentrated the urine is
- Diuretics ('water pills') raise urine chloride while they are working and lower it once their effect wears off, which can make the result misleading.
- Salt intake changes the result: more salt in the diet means more chloride in urine.
- Recent IV fluids that contain chloride, such as saline, can raise it.
- Recent vomiting or other fluid loss can lower it.
Any time. A fresh random (spot) sample is used. Some labs also accept a 24-hour collection. Reflects roughly the last few hours, so it can change quickly with salt intake, fluids and diuretic timing.
Questions you could ask
- How does this result fit with my blood bicarbonate, potassium and blood pressure?
- Could a water pill, my salt intake or recent IV fluids explain a higher urine chloride?
- What other tests would help find the cause?
- Could vomiting or fluid loss explain this result?
- Should we recheck once my fluids and salt levels are back to usual?
Questions people ask
What is a normal urine chloride?
There is no single normal range for a random sample, because the amount of chloride in urine follows what you eat and drink. ARUP, for example, publishes a range only for 24-hour collections (140 to 250 mmol/day) and none for a random sample. Your clinician reads the number together with your blood tests.
Is mEq/L different from mmol/L?
For chloride they are the same number, because each chloride ion carries one charge. A result of 25 mEq/L is 25 mmol/L.
Why was urine chloride ordered after my blood bicarbonate was high?
It helps clinicians sort out why bicarbonate is high. In broad terms, a low urine chloride points toward fluid or chloride loss, and a higher one points toward other causes. It is one piece of the picture, read with your other results.
Show the science and sources
Units
- 1 mmol/L = 1 mmol/L
- 1 mmol/L = 1 mEq/L
For clinicians and researchers
Urine chloride is measured by ion-selective electrode (ARUP) and interpreted against intake, volume status and diuretic timing. In metabolic alkalosis, patients are divided into chloride-responsive (urine Cl- below 20 mmol/L, typically volume contraction after GI or diuretic chloride loss) and chloride-resistant (above 20 mmol/L, typically volume expansion with mineralocorticoid excess or hypertension) groups (Do 2022). Tinawi 2021 uses 20 mmol/L or more for volume expansion, so a value of exactly 20 is not classified the same way in every source. Diuretic use makes the value unreliable: it is elevated while the diuretic acts and low once the effect wears off (Tinawi 2021). A random sample is adequate and a 24-hour collection is usually not needed (Tinawi 2021). Cystic fibrosis can present with either a low or a high urine chloride (Do 2022). Urine chloride also enters the urine anion gap, which has its own entry. Reference intervals for random urine chloride are not standardized, because excretion follows intake. ARUP publishes an interval only for 24-hour excretion (140-250 mmol/day) and none for the mmol/L result.
LOINC 2078-4 (primary), 35676-6. Specimen: urine.
Sources
- Electrolytes, Urine (test 0020498), ARUP Laboratories
- Metabolic Alkalosis Pathogenesis, Diagnosis, and Treatment: Core Curriculum 2022, American Journal of Kidney Diseases 2022;80(4) (2022)
- Pathophysiology, Evaluation, and Management of Metabolic Alkalosis, Cureus 2021 (2021)
- LOINC codes verified with the NLM Clinical Tables LOINC search, U.S. National Library of Medicine
AI-drafted. Awaiting verification. Last reviewed 2026-10-03. How we build and check these pages.