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Anaplracnc

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

This test measures the levels of nuclear antibodies (ANA) in the fluid surrounding the lungs to help diagnose autoimmune conditions.

Quick summary

{"Nuclear antibodies are immune proteins that may attack the body's own cells","This test helps doctors diagnose autoimmune diseases like lupus or rheumatoid arthritis","Abnormal results may indicate inflammation or autoimmune activity in the lungs","The test is performed on fluid extracted from around the lungs (pleural fluid)","Results are interpreted alongside other clinical findings and tests"}

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

Key facts at a glance

LOINC
31542-4
Short code
ANA Plr-aCnc
Synonyms
ANA Plr-aCnc
Category
chemistry
Sample
fluid
Container
Sterile tube
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
86038
Specimen volume
2-5 mL
Stability
Room temperature: 2h, Refrigerated: 24h
Hemolysis max
300
TAT
4–24 hours
Order
routine

What is this test?

The Nuclear Antibody test in pleural fluid measures the amount of antinuclear antibodies (ANA) in the fluid that collects around the lungs. Pleural fluid is a small amount of liquid that sits between the layers of tissue lining the lungs and chest cavity. When too much fluid accumulates, it is called a pleural effusion.

What are nuclear antibodies?

Nuclear antibodies (also called antinuclear antibodies or ANA) are proteins made by your immune system. Normally, antibodies protect you from foreign substances like bacteria and viruses. However, in some people, the immune system mistakenly produces antibodies that attack the body's own healthy cells—this is called an autoimmune reaction. Nuclear antibodies target the nucleus (center) of cells.

Why is this test performed?

Your doctor may order this test if you have a pleural effusion (fluid around the lungs) and they want to determine the cause. Elevated nuclear antibodies in pleural fluid may suggest that an autoimmune condition is affecting the lungs. This helps doctors distinguish between different causes of pleural effusion, such as infections, heart failure, cancer, or autoimmune diseases.

How is the sample collected?

Pleural fluid is collected through a procedure called thoracentesis. During this procedure, a doctor numbs the area and inserts a thin needle into the pleural space to withdraw fluid. The fluid is then sent to a laboratory where it is tested for nuclear antibody levels.

What do the results mean?

Results are typically reported as a titer (a measure of concentration) or as positive/negative. A positive result means nuclear antibodies were detected in the pleural fluid. This finding, combined with your symptoms and other test results, can help diagnose conditions such as systemic lupus erythematosus (SLE), rheumatoid arthritis, scleroderma, or other autoimmune disorders. However, a positive result does not automatically mean you have an autoimmune disease—your doctor will interpret the results in the context of your overall health.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Frequently asked questions

Is this test painful?
The thoracentesis procedure used to collect pleural fluid may cause some discomfort, but the area is numbed with local anesthetic. You may feel pressure or a brief sting during the needle insertion. After the procedure, you may have some soreness at the insertion site.
Are there any risks associated with this test?
The main risks of thoracentesis include bleeding, infection, pneumothorax (collapsed lung), and re-accumulation of fluid. These complications are uncommon. Your healthcare team will take precautions to minimize risks.
Do I need to prepare anything before the test?
Your doctor will provide specific instructions. You may need to avoid certain medications before the procedure. Inform your doctor about all medications you are taking, especially blood thinners.
What happens if my results are positive?
A positive result suggests the presence of nuclear antibodies in the pleural fluid. Your doctor will consider this finding along with your symptoms, medical history, physical examination, and other test results to determine if you have an autoimmune condition. Further testing may be needed to confirm a specific diagnosis.
Can this test diagnose lupus?
This test alone cannot diagnose lupus or any other specific disease. It is one piece of information doctors use to understand what is causing fluid to accumulate around your lungs. A definitive diagnosis of autoimmune diseases like lupus requires combining multiple test results with clinical symptoms.
  1. 1
    MedlinePlus - Antinuclear Antibody TestSource
  2. 2
    Mayo Clinic - Pleural EffusionSource
  3. 3
    Arthritis Foundation - Understanding ANASource

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