Skip to content

Anti-Citrullinated Protein Antibody (ACPA) Screening Test

Published: August 9, 2026Updated: August 17, 2026

This blood test measures antibodies that may indicate inflammation linked to certain types of arthritis, such as rheumatoid arthritis.

Quick summary

["ACPA antibodies can help identify potential arthritis risk or confirm diagnosis in some cases."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC
11561-8
Short code
AChR Block Ab Ser-aCnc
Synonyms
AChR Block Ab Ser-aCnc
Category
coagulation
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
22
Ref high
198
Critical range
— – 10000 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
82553
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 produced by the immune system that attack citrullinated proteins—a process that can occur in joints and other tissues. This test detects their presence in your blood, which may signal an autoimmune response.

Why It’s Ordered

Doctors may order this test if you have symptoms like joint pain, swelling, or stiffness—especially if they suspect rheumatoid arthritis or other inflammatory conditions. It can also be used as part of a broader evaluation for autoimmune diseases.

How the Test Works

A small blood sample is taken, and the lab analyzes it using immunoassay methods to identify ACPA antibodies. The result helps determine if further testing or monitoring is needed.

What to Expect Before the Test

No special preparation is usually required, but you may be asked to fast for 8–12 hours if your blood is drawn early in the morning. Wear comfortable clothing for the blood draw.

Reference range

Adult males: 22-198 U/L; Females: 22-198 U/LN/A

Specimen: serum

No special preparation required. Inform provider of any chest pain or symptoms.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

ACPA Screen

Frequently asked questions

This test is primarily a screening tool. While positive results may raise suspicion for rheumatoid arthritis or other autoimmune conditions, they do not confirm a diagnosis alone. Follow-up tests or clinical evaluation may be needed.
ACPA antibodies are not specific to rheumatoid arthritis but can appear in other inflammatory or autoimmune diseases. A positive result may prompt additional testing, such as rheumatoid factor or imaging studies.
What does a positive result mean?
A positive ACPA test suggests a higher likelihood of rheumatoid arthritis or another autoimmune condition, but it does not guarantee the diagnosis. Your doctor will consider symptoms, other test results, and medical history to make a full assessment.
Can lifestyle changes affect ACPA levels?
There is no direct evidence that lifestyle changes (like diet or exercise) alter ACPA antibody levels. However, managing symptoms of arthritis—such as through physical therapy or medications—can help reduce joint inflammation and improve quality of life.
  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 17, 2026. · Read our editorial policy