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Anti-Citrullinated Protein Antibody (ACPA) by Immunoassay (Serum/Plasma)

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

This test measures antibodies against citrullinated proteins, which are linked to rheumatoid arthritis. It helps assess your risk for or presence of this autoimmune condition.

Quick summary

["ACPA antibodies may indicate early rheumatoid arthritis or help guide treatment decisions."]

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

Key facts at a glance

LOINC
41122-3
Short code
T palldm Ab Spec-aCnc
Synonyms
T palldm Ab Spec-aCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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

What This Test Measures

ACPA antibodies are proteins your immune system mistakenly targets in conditions like rheumatoid arthritis. This test detects their presence in your blood, often as part of screening or monitoring for joint inflammation.

Why It’s Done

Doctors may order this test if you have symptoms like joint pain, swelling, or stiffness—especially if they suspect rheumatoid arthritis. It can also help confirm a diagnosis or track disease activity over time.

Sample Collection

A small blood sample is drawn from your arm, typically in a clinic or lab. The blood is processed into serum or plasma for testing.

What to Expect Before the Test

No special preparation is needed, but inform your provider about medications (e.g., blood thinners) or recent illnesses that might affect results.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

High ACPA levels strongly suggest rheumatoid arthritis, especially in early stages. They’re less common in other autoimmune diseases, making this test useful for differentiating conditions. Results may also help determine disease severity or response to treatment.

Short name

ACPA Antibody Test

Frequently asked questions

What does a positive result mean?
A positive result means your immune system has produced ACPA antibodies, which may indicate rheumatoid arthritis or another autoimmune condition. However, not everyone with these antibodies has symptoms, and false positives can occur. Your doctor will interpret results in the context of your symptoms and other tests.
Can this test be used to diagnose rheumatoid arthritis?
No, this test alone isn’t enough to diagnose rheumatoid arthritis. It’s often used alongside other tests (like rheumatoid factor or physical exams) to support a diagnosis. Your doctor will consider all evidence, including how your symptoms fit with the test results.
How often should I get this test?
Your doctor will decide based on your medical history, symptoms, and treatment needs. Some people with rheumatoid arthritis may get this test periodically to monitor disease activity or response to treatment, but it’s not routine for everyone.
  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