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Serum Immunoblot for Autoantibodies (e.g., Antinuclear Antibodies, Rheumatoid Factor)

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

This test detects antibodies your immune system may produce against your own body’s tissues, which can signal autoimmune conditions like lupus, rheumatoid arthritis, or other inflammatory diseases.

Quick summary

["Helps identify potential autoimmune disorders by checking for unusual antibodies in your blood."]

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

Key facts at a glance

LOINC
94389-4
Short code
Hu1 IgG Ser Ql Line blot
Synonyms
Hu1 IgG Ser Ql Line blot
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
line-blot
CPT
82784
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

An immunoblot (also called a Western blot) is a method that separates and identifies specific proteins (antibodies) in your serum. This test looks for a range of autoantibodies, including those against nuclear components (ANA), cytoplasmic proteins, or rheumatoid factors that bind to immune complexes.

Common Conditions This Test May Help Diagnose

This test is often used as part of a broader evaluation for autoimmune diseases, such as systemic lupus erythematosus (SLE), rheumatoid arthritis, Sjogren’s syndrome, or mixed connective tissue disease. It may also be used to monitor disease activity or guide treatment decisions.

How the Test Works

A small blood sample is drawn and processed to isolate serum. Antibodies in the serum are then separated and detected using specific probes. Fluorescent or colorimetric markers reveal which antibodies are present, allowing for qualitative identification.

Preparation for the Test

No special preparation is needed. You may eat or drink as usual before your blood draw. If you’re on certain medications that affect immune function, let your healthcare provider know before testing.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Autoantibody Profile Screening

Frequently asked questions

Why might this test be ordered?
Your doctor may order this test if you have symptoms like joint pain, fatigue, rash, or unexplained fever, or if you have a family history of autoimmune diseases. It can also help confirm a diagnosis or assess disease progression in patients already suspected of having an autoimmune condition.
What does a positive result mean?
A positive result indicates the presence of autoantibodies, which may suggest an autoimmune disorder. However, a positive test alone does not confirm a diagnosis—additional tests and clinical evaluation are needed. Some people test positive without symptoms or an underlying condition.
Can this test be used to monitor treatment?
Yes, this test can help track changes in antibody levels over time, which may indicate how well your treatment is working or if your condition is improving or worsening.
  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