Smooth Muscle Antibodies
The Smooth Muscle Antibodies (SMA) test detects autoantibodies linked to autoimmune liver conditions. It is commonly used in the investigation of autoimmune hepatitis and unexplained liver inflammation.
Turnaround time
5 days
Biomarkers count
1
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Details about Smooth Muscle Antibodies
What is the Smooth Muscle Antibodies (SMA) test?
The Smooth Muscle Antibodies (SMA) test is a blood test that detects autoantibodies directed against proteins found in smooth muscle cells. These antibodies are most commonly associated with autoimmune hepatitis, a condition where the immune system attacks liver tissue.
SMA testing is usually performed using immunological techniques such as immunofluorescence. The presence and titre (level) of antibodies provide important diagnostic information when assessing liver-related symptoms or abnormal liver function tests.
Why do I need a Smooth Muscle Antibodies test?
Autoimmune liver disease can be difficult to diagnose because symptoms are often non-specific or mild in early stages. SMA testing helps identify an autoimmune cause when routine liver tests are abnormal or when symptoms persist without a clear explanation.
You may need this test if you have:
- Persistently abnormal liver function tests (LFTs)
- Unexplained fatigue or weakness
- Jaundice (yellowing of skin or eyes)
- Abdominal discomfort or liver enlargement
- Suspected autoimmune hepatitis
- Other autoimmune conditions with liver involvement
Benefits of the Smooth Muscle Antibodies test
- Supports diagnosis of autoimmune hepatitis
One of the key antibodies associated with the condition. - Helps explain abnormal liver tests
Identifies immune-mediated causes of liver inflammation. - Non-invasive blood test
No imaging or biopsy required for initial assessment. - Guides specialist referral
Supports hepatology or gastroenterology input. - Useful alongside other autoantibody tests
Often interpreted with ANA, LKM, and AMA. - Detects disease even with mild symptoms
Useful in early or atypical presentations. - Supports long-term disease monitoring
Titres may change with disease activity. - Improves diagnostic confidence
Adds objective evidence to clinical evaluation.
Step-by-step – How we offer this test
Option 1: Clinic-based blood test (UK-wide)
- Choose your nearest UK clinic
- Attend your appointment
- Blood sample taken by a clinician
- Sample analysed for smooth muscle antibodies
Option 2: Home or hotel visit (+£60, UK-wide)
- Qualified phlebotomist attends your location
- Blood sample taken at home or hotel
- No travel required
- Same laboratory analysis and reporting
Your results explained
Negative SMA result
No smooth muscle antibodies detected.
Typical UK interpretation:
- Negative or below laboratory cut-off
This makes autoimmune hepatitis less likely but does not completely exclude it.
Low-positive SMA result
Low levels of smooth muscle antibodies detected.
Typical UK interpretation:
- Low titre positivity
May be seen in early autoimmune hepatitis or occasionally in other liver or autoimmune conditions.
High SMA levels
High titres of smooth muscle antibodies detected.
Typical UK interpretation:
- Moderate to high titre positivity
Strongly supportive of autoimmune hepatitis, particularly when combined with abnormal liver enzymes and other autoantibodies.
How It Works
Simple steps to get your results
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Visit or Test at Home
Attend one of our UK or London clinics, arrange a home nurse visit, or use a finger-prick kit where available.
Get Your Results
Your sample is analysed by accredited UK laboratories, with secure results delivered directly to you.
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WhatsApp UsHow to Prepare for Your Test
Follow these guidelines for accurate results
Sample Timing
Where possible, attend your blood test between 7am and 12pm. Please wait until any short-term illness or infection has fully resolved before testing. Avoid intense exercise for 24–48 hours beforehand, as this can affect certain markers.
Fasting & Hydration
Fasting is not always required, but some tests may recommend it. If fasting is advised, avoid food for 8–12 hours before your appointment and drink water only. Stay well hydrated, as this helps with sample collection and accuracy.
Medications & Supplements
Continue prescribed medications unless advised otherwise by your clinician. Avoid vitamin, mineral, or biotin supplements for at least 24–48 hours before your test, as these can interfere with results. If you are unsure about any medication or supplement, please let us know before your appointment.
Hormones & Menstrual Cycle
For hormone-related tests, timing within your menstrual cycle may be important. If relevant, follow any specific guidance provided on your test page.
If you have any questions or special circumstances, our team is happy to advise before your appointment.