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Anti-MDA5 Antibody (Topoisomerase I Immunoblot)

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

This test detects antibodies against the MDA5 protein, which may help identify certain types of inflammatory myopathies or autoimmune conditions.

Quick summary

["This test helps diagnose rare inflammatory diseases linked to specific autoantibodies."]

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

Key facts at a glance

LOINC
82994-5
Short code
MDA5 IgG Ser Ql Line blot
Synonyms
MDA5 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

The test looks for the presence of anti-MDA5 antibodies in your serum. These antibodies target a protein called MDA5, which is involved in immune responses. The test uses an immunoblot method to confirm the presence of these antibodies if they are detected by initial screening tests.

Why It Might Be Ordered

Your healthcare provider may order this test if you have symptoms like muscle weakness, skin rashes, or other signs of inflammatory myopathies (such as dermatomyositis or polymyositis) that don’t respond to standard treatments.

Sample Collection and Preparation

A blood sample is taken from a vein in your arm. The serum portion is separated and sent to the lab for analysis. This test requires a fresh or stored serum sample for accurate results.

What to Expect Before the Test

No special preparation is needed, but inform your provider about any medications you’re taking, as some may affect test results.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Anti-MDA5 Antibody (Serum)

Frequently asked questions

How long does it take to get results?
Results are typically available within 3 to 5 business days, depending on lab processing times. Follow up with your healthcare provider to discuss the findings.
What does a positive result mean?
A positive result indicates the presence of anti-MDA5 antibodies, which may confirm a diagnosis of anti-MDA5 dermatomyositis or help differentiate it from other inflammatory conditions. Your provider will interpret results in the context of your symptoms and medical history.
Can this test be done at home?
No, this test requires a lab sample collected by a healthcare professional. It is not available for at-home testing.
  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