Also Known As
Antibodies to Saline-extracted Antigens
Anti-RNP
Anti-Ribonucleoprotein
Anti-U(1)RNP
Anti-SmRNP
Anti-SSA
SSA (Ro)
Anti-Sjögren Syndrome A
Anti-SSB
SSB (La)
Anti-Sjögren Syndrome B
Anti-Sm
Smith Antibody
Scl-70
Anti-Topoisomerase
Scleroderma Antibodies
Anti-Jo-1
Antihistidyl Transfer RNA Synthase Antibodies
Formal Name
Extractable Nuclear Antigen Antibodies
This article was last reviewed on
This article waslast modified on 10 February 2022.
At a Glance
Why Get Tested?

To help diagnose and distinguish between autoimmune disorders and in some cases to monitor autoimmune disease progression

When To Get Tested?

When your antinuclear antibody (ANA) test is positive; when you have symptoms that suggest an autoimmune disorder; and in some cases when monitoring the activity of an autoimmune disorder

Sample Required?

A blood sample taken from a vein in your arm

Test Preparation Needed?

No test preparation needed

On average it takes 7 working days for the blood test results to come back from the hospital, depending on the exact tests requested. Some specialist test results may take longer, if samples have to be sent to a reference (specialist) laboratory. The X-ray & scan results may take longer. If you are registered to use the online services of your local practice, you may be able to access your results online. Your GP practice will be able to provide specific details.

If the doctor wants to see you about the result(s), you will be offered an appointment. If you are concerned about your test results, you will need to arrange an appointment with your doctor so that all relevant information including age, ethnicity, health history, signs and symptoms, laboratory and other procedures (radiology, endoscopy, etc.), can be considered.

Lab Tests Online-UK is an educational website designed to provide patients and carers with information on laboratory tests used in medical care. We are not a laboratory and are unable to comment on an individual's health and treatment.

Reference ranges are dependent on many factors, including patient age, sex, sample population, and test method, and numeric test results can have different meanings in different laboratories.

For these reasons, you will not find reference ranges for the majority of tests described on this web site. The lab report containing your test results should include the relevant reference range for your test(s). Please consult your doctor or the laboratory that performed the test(s) to obtain the reference range if you do not have the lab report.

For more information on reference ranges, please read Reference Ranges and What They Mean.

What is being tested?

An extractable nuclear antigen (ENA) panel detects the presence of one or more autoantibodies in the blood that react with proteins in the cell nucleus. These proteins are known as "extractable" because they can be removed from cell nuclei using saline.

Autoantibodies are produced when a person's immune system mistakenly targets and attacks the body's own tissues. This attack can cause inflammation, tissue damage, and other signs and symptoms that are associated with an autoimmune disorder.

Certain autoimmune disorders are characteristically associated with the presence of one or more anti-ENA antibodies. This association can be used to help diagnose an autoimmune disorder and to distinguish between disorders.

The ENA panel typically consists of a group of 4 or 6 autoantibody tests. The number of tests performed will depend on the laboratory and the needs of the health practitioners and patients it serves. Individual ENA panel tests can also be requested separately.

A 4-test ENA panel will include:

Autoantibody Test Formally Known As
Anti-RNP Anti-U(1)RNP, Anti-Ribonucleoprotein
Anti-Sm Smith Antibody
Anti-SS-A (Ro) Anti-Sjögren Syndrome A
Anti-SS-B (La) Anti-Sjögren Syndrome B

A 6-test ENA panel will include the four tests listed above as well as:

Autoantibody Test Formally Known As
Scl-70 Scleroderma Antibodies; anti-topoisomerase
Anti-Jo-1 Antihistidyl Transfer RNA Synthase Antibodies
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Common Questions
  • How is it used?

    The ENA panel is usually requested following a positive ANA test for people who have signs and symptoms of an autoimmune disorder.

    The 4-test ENA panel is used to help diagnose mixed connective tissue disease (MCTD), systemic lupus erythematosus (SLE), and Sjögren syndrome. The 6-test ENA panel can also help identify scleroderma (systemic sclerosis) and polymyositis/dermatomyositis (inflammatory myopathies).

    For more on these diseases, visit the National Institute of Arthritis and Musculoskeletal and Skin Diseases web site.

    An ENA panel may also be used to monitor the activity of a particular autoimmune disorder.

  • When is it requested?

    An ENA panel is requested when a person has signs and symptoms that could be due to an autoimmune disorder and has a positive ANA test. Signs and symptoms of autoimmune disorders are highly variable and can involve several different areas of the body. They may include:

    In most cases, an ENA panel will not be requested when a person has a negative ANA test. If no antinuclear antibodies are present, then the person is extremely unlikely to test positive for a specific antinuclear antibody (which is what the ENA panel tests). On occasion, patients with Sjogren’s Syndrome may have a negative ANA but a positive SSA because SSA is sometimes poorly expressed in the Hep-2 cell used to detect ANA.

    As a result, the ENA panel, or one or more of its component tests, may be repeated when initial test results are negative but clinical signs persist. Testing may also be requested when a person has been diagnosed with an autoimmune disorder and at some point develops symptoms that may be due to an additional autoimmune disorder. A health practitioner also may request testing to monitor the activity and/or progression of certain autoimmune disorders like poly/dermatomyositis, in which Jo-1 titres are predictive of clinical course.

  • What does the test result mean?

    Diagnoses of autoimmune diseases are typically based on the characteristic signs and symptoms and on results of autoantibody tests. ENA panel results help to detect and distinguish between different autoimmune disorders. Studies have shown that each of these autoantibodies is frequently detected in people who have a specific autoimmune disorder and is less frequently detected or not detected in those without the disease.

    The pattern of positive and negative results obtained with an ENA panel is evaluated in conjunction with a person's clinical findings. If someone has symptoms that suggest a specific autoimmune disorder and the corresponding ENA autoantibody is positive, then it is likely that the person has that condition.

    If a person has symptoms but the autoantibody is not present, it could mean that the individual has not yet developed the autoantibody, or it may mean that the person's symptoms are due to another condition.

    Interpretation of results for the tests included in an ENA panel are provided in the table below. A positive test result means that the person has more of that autoantibody in their blood than the designated reference value. 

    Autoantibody Test Results That Support an Autoimmune Disorder Diagnosis
    Anti-RNP Positive result seen in 95-100% of mixed connective tissue disease (MCTD) cases; may also be positive with SLE and scleroderma
    Anti-Sm Positive result seen in 30% of those with SLE; very specific antibody marker for this disease
    Anti-SS-A (Ro) Positive result seen in 75% of those with Sjögren's syndrome; may also be positive with SLE and scleroderma
    Anti-SS-B (La) Positive result seen in 60% of those with Sjögren's syndrome; may also be positive with SLE and scleroderma; rarely present without anti-SS-A
    Scl-70 Positive result seen in 60% of those with scleroderma (systemic sclerosis); highly specific antibody marker for this disease
    Anti-Jo-1 Positive result seen in 30% of those with polymyositis; may be positive with pulmonary fibrosis but little else
  • Is there anything else I should know?

    ENA are referred to as "extractable" or "saline-extracted" because of the laboratory method originally used to discover and work with these antigens. More than 100 antigens have been identified in this way, but only a few are routinely tested.

  • Will my ENA autoantibodies ever go away?

    Levels may fluctuate, but once a person has developed an autoantibody, he or she will continue to have it. For the most part, these antibodies are not reliable indicators of disease activity.

  • Can the ENA panel be performed in my doctor's surgery?

    No. The ENA tests require specialised equipment and skilled laboratory personnel. Your sample will need to be sent to a laboratory that performs these tests.

  • My doctor requested only a 4-test ENA panel, not a 6-test ENA panel. Will something be missed?

    The panel performed will usually be the one offered by the laboratory that tests your sample. If a 4-test panel is requested and your doctor is interested in additional tests, he or she can request the others separately as needed to ensure that nothing is missed.

  • Should everyone have an ENA panel done?

    Autoantibody testing is only necessary when a person has symptoms that suggest an autoimmune disorder. Most people will never need to have an ENA panel performed.

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