Also Known As
Antibodies to Saline-extracted Antigens
SSA (Ro)
Anti-Sjögren Syndrome A
SSB (La)
Anti-Sjögren Syndrome B
Smith Antibody
Scleroderma Antibodies
Antihistidyl Transfer RNA Synthase Antibodies
Formal Name
Extractable Nuclear Antigen Antibodies
This article was last reviewed on
This article waslast modified on November 5, 2017.
At a Glance
Why Get Tested?

To help diagnose and distinguish between autoimmune disorders as well as 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; when monitoring the activity of an autoimmune disorder

Sample Required?

A blood sample drawn from a vein in your arm

Test Preparation Needed?


You may be able to find your test results on your laboratory's website or patient portal. However, you are currently at Lab Tests Online. You may have been directed here by your lab's website in order to provide you with background information about the test(s) you had performed. You will need to return to your lab's website or portal, or contact your healthcare practitioner in order to obtain your test results.

Lab Tests Online is an award-winning patient education website offering information on laboratory tests. The content on the site, which has been reviewed by laboratory scientists and other medical professionals, provides general explanations of what results might mean for each test listed on the site, such as what a high or low value might suggest to your healthcare practitioner about your health or medical condition.

The reference ranges for your tests can be found on your laboratory report. They are typically found to the right of your results.

If you do not have your lab report, consult your healthcare provider or the laboratory that performed the test(s) to obtain the reference range.

Laboratory test results are not meaningful by themselves. Their meaning comes from comparison to reference ranges. Reference ranges are the values expected for a healthy person. They are sometimes called "normal" values. By comparing your test results with reference values, you and your healthcare provider can see if any of your test results fall outside the range of expected values. Values that are outside expected ranges can provide clues to help identify possible conditions or diseases.

While accuracy of laboratory testing has significantly evolved over the past few decades, some lab-to-lab variability can occur due to differences in testing equipment, chemical reagents, and techniques. This is a reason why so few reference ranges are provided on this site. It is important to know that you must use the range supplied by the laboratory that performed your test to evaluate whether your results are "within normal limits."

For more information, please read the article 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 ordered 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

How is the sample collected for testing?

A blood sample is obtained by inserting a needle into a vein in the arm.

Is any test preparation needed to ensure the quality of the sample?

No test preparation is needed.

Accordion Title
Common Questions
  • How is it used?

    The ENA panel is usually ordered 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 and polymyositis/dermatomyositis. 

    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 ordered?

    An ENA panel is ordered 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 ordered 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).

    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 ordered 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 order testing to monitor the activity and/or progression of a known autoimmune disorder.

  • 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; 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
  • 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.

  • Can the ENA panel be performed at my doctor's office?

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

  • My doctor ordered 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 ordered and your doctor is interested in additional tests, he or she can order 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.
View Sources

Sources Used in Current Review

Bartels, Christie M., et al. (Updated Jan. 28, 2013.) Systemic Lupus Erythematosus (SLE) Workup. Medscape online. Available online at through Accessed January 2014.

Orton, Susan M., et al. (March 2004). Practical Evaluation of Methods for Detection and Specificity of Autoantibodies to Extractable Nuclear Antigens. American Society for Microbiology, Clinical and Vaccine Immunology online. Available online at through Accessed January 2014.

Antibodies to Extractable Nuclear Antigens. Children's Hospitals and Clinics of Minnesota. Available online at through Accessed January 2014.

Kavanaugh, Arthur, et al. (January 2000.) Guidelines for Clinical Use of the Antinuclear Antibody Test and Tests for Specific Autoantibodies to Nuclear Antigens. Archives of Pathology and Laboratory Medicine. Available online through Accessed January 2014.

Sources Used in Previous Reviews

(© 1995-2010). Unit Code 89035: Antibody to Extractable Nuclear Antigen Evaluation, Serum. Mayo Clinic, Mayo Medical Laboratories [On-line information]. Available online at through Accessed March 2010.

(© 2006-2010). Extractable Nuclear Antigen Antibodies (RNP, Smith, SSA, & SSB): 0050652. ARUP's Laboratory Test Directory [On-line information]. Available online at through Accessed March 2010.

Hill, H. and Tebo. (Updated 2009 November). Mixed Connective Tissue Disease – MCTD. ARUP Consult [On-line information]. Available online at through Accessed March 2010.

Hill, H. and Tebo. (Updated 2009 August). Connective Tissue Diseases. ARUP Consult [On-line information]. Available online at through Accessed March 2010.

(© 1995-2010). Unit Code 83631: Connective Tissue Diseases Cascade, Serum. Mayo Clinic, Mayo Medical Laboratories [On-line information]. Available online at through Accessed March 2010.

Klein-Gitelman, M. (Updated 2009 September 29). Mixed Connective Tissue Disease. eMedicine [On-line information]. Available online at through Accessed March 2010.

Hildebrand Jr., G. and Battafarano, D. (Updated 2009 July 24). Undifferentiated Connective Tissue Disease. eMedicine [On-line information]. Available online at through Accessed March 2010.

Hajj-ali, R. (Revised 2008 February) Mixed Connective Tissue Disease (MCTD). Merck Manual for Healthcare Professionals [On-line information]. Available online at through Accessed March 2010.

Pagana, K. D. & Pagana, T. J. (© 2007). Mosby's Diagnostic and Laboratory Test Reference 8th Edition: Mosby, Inc., Saint Louis, MO. Pp 81-82.

Wu, A. (© 2006). Tietz Clinical Guide to Laboratory Tests, 4th Edition: Saunders Elsevier, St. Louis, MO. Pp 128-129, 136-139.

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