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Anti-Muscle-Specific Tyrosine Kinase (MUSK) Antibody, Serum/Plasma

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

This test measures the presence of antibodies against the MUSK protein, which can help diagnose certain autoimmune conditions affecting muscles.

Quick summary

["This test may help identify myasthenia gravis or related muscle disorders linked to MUSK antibodies."]

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

Key facts at a glance

LOINC
32702-3
Short code
Mus Sarcolemma Ab Ser Ql
Synonyms
Mus Sarcolemma Ab Ser Ql
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

Why This Test Might Be Ordered

Your doctor may recommend this test if you have symptoms like muscle weakness, especially in the eyes or limbs, or if they suspect an autoimmune muscle disorder. It’s often used alongside other tests to confirm a diagnosis or guide treatment decisions.

What to Expect Before the Test

No special preparation is needed for this blood test. You may be asked to fast for 8–12 hours before your blood draw, but always follow your doctor’s instructions.

How the Test Works

A small sample of your blood is drawn and sent to a lab. The lab uses an immunoassay method to detect the presence of MUSK antibodies in your serum or plasma.

What the Results Mean

Positive results indicate the presence of MUSK antibodies, which may suggest a specific type of autoimmune myasthenia gravis or related muscle disorder. Results alone don’t diagnose the condition but support further evaluation.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Elevated MUSK antibodies are strongly associated with a rare form of autoimmune myasthenia gravis called MUSK-MG. This test helps distinguish this subtype from other forms of myasthenia gravis or muscle disorders, guiding targeted treatment (e.g., immunotherapy). Early detection can improve outcomes by allowing timely intervention.

Short name

MUSK Antibody (Serum/Plasma)

Frequently asked questions

What does a positive result mean?
A positive result suggests you may have MUSK antibodies, which are linked to a specific type of muscle weakness. Your doctor will discuss next steps, such as additional testing or treatment options.
How often should I get this test?
Your doctor will determine how often to repeat this test based on your symptoms, treatment response, and overall health. Follow-up may be needed if symptoms persist or change.
Can lifestyle changes affect test results?
Lifestyle factors like diet or stress may influence symptoms but are unlikely to directly alter antibody levels detected in this test. Always report any changes to your doctor.
  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