A patient-friendly guide to the cholesterol test, including what it measures, how blood is drawn, and why it matters for your heart health.
A test that measures the level of chloride in the fluid collected from around the lungs.
{"Measures chloride concentration in fluid between the lungs and chest wall","Helps determine the cause of fluid buildup in the chest","Low pleural fluid chloride may suggest tuberculosis","Results are compared to blood chloride levels","Used together with other tests to diagnose the type of pleural effusion"}
Key facts at a glance
- LOINC
- 53627-6
- Short code
- CL_PF
- Synonyms
- Chloride Plr-sCnc
- Category
- electrolyte
- Sample
- fluid
- Container
- Sterile collection container, preferably plastic (not glass). May also be collected in lavender-top (EDTA) tube if concurrent cell count is ordered.
- Units
- not specified
- Ref low
- 100
- Ref high
- 110
- Critical range
- 55 not specified – —
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- ≥ 0 years
- Method
- Ion-selective electrode (ISE) potentiometry
- CPT
- 82436
- SNOMED
- 314589001
- Specimen volume
- Minimum 0.5 mL; preferred 1-2 mL for adequate testing.
- Stability
- Room temperature: 24 hours. Refrigerated (2-8°C): 72 hours. Frozen (-20°C): 1 month. Avoid repeated freeze-thaw cycles.
- Hemolysis max
- 50
- Lipemia max
- 300
- Icterus max
- 20
- TAT
- 1–4 hours
- Order
- routine
This test measures the amount of cholesterol and triglycerides in your blood. Cholesterol is a waxy, fat-like substance that your body needs to build cells and make vitamins and hormones, but too much can clog your arteries and increase your risk of heart disease and stroke. The test gives you a breakdown of LDL (bad) cholesterol, HDL (good) cholesterol, and total cholesterol.
The Pleural Fluid Chloride test measures the amount of chloride, an important electrolyte, in the pleural fluid. Pleural fluid is the small amount of liquid that naturally exists in the space between your lungs and chest wall (pleural space). When too much fluid collects here, it's called pleural effusion.
To collect the sample, a healthcare professional will clean a small area on your arm with an antiseptic wipe. Then they will wrap an elastic band around your upper arm to make your veins more visible. Next, they will insert a needle into a vein and draw a small amount of blood into a vial. After the needle is removed, you'll be asked to apply pressure with a cotton ball to stop any bleeding, and a bandage will be placed over the site.
A healthcare provider will perform a procedure called thoracentesis. They will clean an area on your back, num the skin with local anesthetic, and then insert a thin needle to withdraw fluid from the pleural space. The fluid sample is sent to a laboratory for analysis.
This test is important because high cholesterol usually has no symptoms, so you might not know you're at risk. By catching elevated levels early, you can work with your doctor to make lifestyle changes or take medications to lower your cholesterol, which can significantly reduce your chances of having a heart attack or stroke. Regular testing is especially crucial if you have risk factors like diabetes, high blood pressure, or a family history of heart disease.
Chloride is a negatively charged electrolyte that helps maintain fluid balance in your body. Measuring chloride in pleural fluid helps doctors understand what's causing the fluid buildup. Different conditions produce fluids with different chemical compositions.
Reference range
100-110 mmol/Lnot specified
No special preparation required
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
The pleural fluid chloride level helps distinguish between different types of pleural effusions. When pleural fluid chloride is significantly lower than blood chloride levels (typically less than 55 mmol/L), it often indicates a condition called exudative effusion, commonly associated with tuberculosis, lymphoma, or rheumatoid arthritis. Transudates (caused by heart failure, liver disease, or kidney disease) typically have chloride levels similar to blood. This test is part of a broader analysis called Light's criteria, which also includes protein and lactate dehydrogenase (LDH) measurements.
In tuberculosis pleuritis, the pleural fluid chloride is characteristically low because of active transport of chloride into the pleural space by inflammatory cells. This finding, combined with other clinical features, can support a diagnosis of tuberculous pleurisy.
Frequently asked questions
Is the thoracentesis procedure painful?
How long does it take to get results?
What do abnormal results mean?
Are there any risks from this test?
Sources
- 1
- 2
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.
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 10, 2026. · Read our editorial policy