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Serum Axillary Sweat Electrolyte Profile (Free Sodium, Chloride, Potassium)

Published: August 9, 2026Updated: August 16, 2026

This test measures the levels of sodium, chloride, and potassium in sweat collected from your armpit. It helps assess how well your body regulates electrolytes, which is important for nerve and muscle function.

Quick summary

["This sweat test helps diagnose conditions like cystic fibrosis or other electrolyte disorders by checking how your body handles essential minerals."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
18509-0
Short code
T wave axis HP RefB
Synonyms
T wave axis HP RefB
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ekg
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

Why This Test Is Done

Your doctor may recommend this test if you have symptoms like frequent infections, poor growth, or digestive issues. It’s also used in diagnosing conditions like cystic fibrosis, which can affect sweat electrolyte levels.

What to Expect Before the Test

You’ll wear a special bandage on your arm for 24 hours to collect sweat. The bandage is removed, and the sweat is tested for electrolytes. No special preparation is needed beyond avoiding sweat-inducing activities (like exercise) before testing.

What the Results Mean

Higher-than-normal levels of sodium, chloride, or potassium in sweat can indicate problems with sweat regulation, which may be linked to genetic conditions like cystic fibrosis. Lower-than-normal levels might suggest other electrolyte imbalances.

Common Conditions Linked to Sweat Electrolyte Tests

This test is primarily used to diagnose cystic fibrosis and other inherited disorders affecting sweat glands. It can also help monitor conditions where electrolyte balance is critical, such as certain metabolic or endocrine disorders.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Axillary Sweat Electrolyte Test

Frequently asked questions

What causes sweat to be tested for electrolytes?
Sweat electrolyte testing is most commonly ordered if you have symptoms of cystic fibrosis (like recurrent lung infections, poor weight gain, or digestive problems) or if a family history suggests a genetic sweat disorder. It may also be used in research or specialized clinical settings for other electrolyte-related conditions.
How long does it take to get results from this test?
Results from this sweat test are typically available within a few days to a couple of weeks, depending on the lab’s processing time. Your doctor will discuss the findings with you during your follow-up visit.
Can I take medications before this test?
Yes, you may need to avoid certain medications or supplements that could affect sweat production (like diuretics or some vitamins). Always follow your doctor’s instructions for any pre-test preparations.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy