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Anti-Citrullinated Protein Antibody (ACPA) – Serum

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

This blood test measures antibodies against citrullinated proteins, which are linked to certain types of arthritis. These antibodies help identify rheumatoid arthritis (RA) and may also be present in other inflammatory conditions.

Quick summary

["ACPA antibodies can help diagnose rheumatoid arthritis and guide treatment decisions."]

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

Key facts at a glance

LOINC
53028-7
Short code
cCP Ab Ser Ql
Synonyms
cCP Ab Ser Ql
Category
coagulation
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

Why This Test Might Be Ordered

Your doctor may recommend this test if you have symptoms of rheumatoid arthritis, such as joint pain, swelling, or stiffness—especially if they appear early in the disease. It may also be used to monitor disease activity or assess response to treatment in people already diagnosed with RA.

What to Expect Before the Test

No special preparation is needed. You’ll have a small needle inserted into your arm to draw blood. It typically takes a few minutes, and you may feel a brief pinch. If you’re on blood thinners, let your doctor know before the test.

What the Results Mean

Positive results (high antibody levels) strongly suggest rheumatoid arthritis, but they don’t confirm the diagnosis alone. Your doctor will consider other factors, like symptoms, physical exam, and possibly other tests. Some people with RA may have negative results early in the disease.

Common Conditions Linked to ACPA Antibodies

ACPA antibodies are most strongly associated with rheumatoid arthritis, but they can also appear in other inflammatory conditions like psoriatic arthritis or certain types of lupus. They’re rarely found in healthy individuals.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: Role in Diagnosis and Monitoring

Short name

ACPA Antibody (Serum)

Frequently asked questions

Is this test painful?
Most people describe the blood draw as mild discomfort, similar to a typical vaccine shot. The needle is small, and the procedure takes only a few minutes. If you’re anxious, ask your healthcare provider about numbing cream or other options.
Can I eat or drink before this test?
You can eat and drink normally before the test unless instructed otherwise. No fasting is required for this blood test.
How long will I need to wait for results?
Results are usually available within a few days to a week, depending on your lab. Your doctor will discuss them with you during your follow-up visit.
  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