Smooth Muscle Antibody (Serum) – Immunoassay
This test measures antibodies in your blood that may indicate an autoimmune response targeting smooth muscle proteins, often linked to conditions like autoimmune hepatitis or connective tissue disorders.
["This test helps diagnose certain autoimmune conditions affecting organs like the liver or heart."]
Key facts at a glance
- LOINC
- 30557-3
- Short code
- Smooth muscle IgG Ser Ql
- Synonyms
- Smooth muscle IgG 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
- 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 detects the presence of antibodies (specifically smooth muscle antibodies) in your serum. These antibodies are part of your immune system’s response and can target proteins found in smooth muscle tissues, which are present in organs such as the liver, heart, and blood vessels. The test is typically performed using an immunoassay method to identify these antibodies with high sensitivity.
Why It’s Done
Your healthcare provider may order this test if you have symptoms like fatigue, abdominal pain, joint swelling, or unexplained liver enzyme elevations. It’s also used in the evaluation of autoimmune diseases such as autoimmune hepatitis, scleroderma, or other connective tissue disorders.
Sample Collection and Preparation
A blood sample is drawn from a vein, usually in your arm. The blood is then processed to separate the serum (the liquid part without clotting factors), which is sent to the lab for testing. No special preparation is needed, but fasting may be advised depending on your specific clinical situation.
Interpretation and Results
Results are qualitative (positive or negative) and indicate whether antibodies are present. A positive result suggests an autoimmune response, but it doesn’t definitively diagnose a condition. Further testing and clinical correlation are required for diagnosis.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Positive smooth muscle antibody results are often associated with autoimmune hepatitis, a condition where the immune system attacks the liver. They can also appear in other autoimmune disorders like systemic sclerosis (scleroderma) or mixed connective tissue disease. While this test is a useful screening tool, it should be interpreted alongside other clinical findings, symptoms, and additional tests to guide diagnosis and treatment planning.
Short name
Smooth Muscle Antibody (Serum)
Frequently asked questions
What does a positive result mean?
Can lifestyle changes affect this test?
How often will I need this test?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
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.
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