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24-Hour Sweat Sodium and Potassium Quantification (Quantitative Sweat Electrolytes)

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

This test measures the amount of sodium and potassium lost through your sweat over 24 hours. It helps diagnose conditions like cystic fibrosis or other genetic disorders affecting sweat production.

Quick summary

["This test helps identify whether your body loses too much salt or potassium through sweat, which can cause serious health issues."]

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

Key facts at a glance

LOINC
2958-7
Short code
Sodium/Potassium Sweat-sRto
Synonyms
Sodium/Potassium Sweat-sRto
Category
electrolyte
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
136
Ref high
145
Critical range
120 N/A – 160 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
84295
SNOMED
110741000
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 dehydration, unexplained weight loss, or a family history of conditions like cystic fibrosis. It’s also used to monitor people with known sweat disorders.

What to Expect Before the Test

You’ll wear a special bandage on your arm or leg for 24 hours to collect sweat. The bandage is changed every few hours to collect samples. You’ll need to stay hydrated and avoid strenuous activity during this time.

What the Test Results Mean

Low or high levels of sodium or potassium in sweat can indicate problems with how your body regulates fluids and electrolytes. Your doctor will compare your results to standard ranges to determine if further testing or treatment is needed.

Common Conditions Linked to Sweat Electrolytes

Abnormal sweat sodium and potassium levels are often linked to genetic disorders like cystic fibrosis, which affects the lungs and digestive system. Other conditions may include certain autoimmune diseases or metabolic disorders.

Reference range

Adult: 136-145 mmol/LN/A

Specimen: serum

No special preparation required. Stay well hydrated.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Sweat electrolytes (Na+, K+)

Frequently asked questions

How does sweat testing differ from regular blood tests for sodium and potassium?
Sweat testing specifically measures electrolytes lost through sweat, not those in your blood. Blood tests check for electrolyte levels inside your body, while sweat tests focus on what’s excreted through the skin, which can reveal genetic or metabolic issues not visible in bloodwork alone.
What should I do if I have high sweat sodium or potassium levels?
If your results show abnormal levels, your doctor may recommend lifestyle changes (like dietary adjustments or hydration strategies) or further testing to identify the underlying cause. Follow their guidance closely.
Can I take medications before the sweat test?
Some medications may affect sweat production or composition. Always inform your healthcare provider about all medications, supplements, or treatments you’re taking before the test.
  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