ANA (Antinuclear Antibody) Test

Diagram shows what pathologists see under the microscope in an ANA test

We normally have antibodies in our blood that repel invaders in our bodies, such as viruses and bacteria. Antinuclear antibodies (ANAs) are unusual antibodies, detectable in the blood, that have the capability of binding to certain structures within the nucleus of the cells. The nucleus is the innermost core within the body's cells and contains DNA, the primary genetic material. ANAs are found in patients whose immune systems may be predisposed to cause inflammation against their own body tissues. Antibodies that are directed against one's own tissues are referred to as autoantibodies. The propensity for the immune system to work against its own body is referred to as autoimmunity. ANAs suggest the possible presence of autoimmunity. Therefore, when they are detected in a patient's blood (referred to as a "positive" result in an ANA test), doctors will consider the possibility that an autoimmune illness exists in that patient.

Autoimmune diseases are conditions in which there is a disorder of the immune system characterized by the abnormal production of antibodies (autoantibodies) directed against the tissues of the body. Autoimmune diseases typically feature inflammation of various tissues of the body. Frequently, ANAs are found in patients with a number of different autoimmune diseases, such as

• systemic lupus erythematosus,
• Sjögren's syndrome,
• rheumatoid arthritis,
• polymyositis,
• scleroderma,
• Hashimoto's thyroiditis,
• juvenile diabetes mellitus,
• Addison disease,
• vitiligo,
• pernicious anemia,
• glomerulonephritis, and
• pulmonary fibrosis.

The ANA test can play a crucial role in diagnosing and monitoring autoimmune conditions. ANAs can also be found in patients with conditions that are not considered classic autoimmune diseases, such as chronic infections and certain cancers, as well as in some healthy individuals. This highlights the importance of interpreting the ANA test as part of a broader clinical evaluation rather than in isolation. Health care providers need to consider the patient's symptoms, medical history, and other laboratory results when interpreting ANA test findings. By doing so, they can better understand the underlying cause of the positive ANA result and develop an appropriate treatment plan if an autoimmune disorder is diagnosed.

The ANA blood test was designed by Dr. George Friou in 1957. The ANA test is performed using a blood sample. An ANA test is performed by testing the blood in the laboratory. The antibodies in the serum of blood are exposed in the laboratory to cells. It is then determined whether or not antibodies are present that react to various parts of the nucleus of cells. Thus, the term anti-"nuclear" antibody. The ANA test specifically looks for the presence of ANA antibodies.

Fluorescence techniques are frequently used to actually detect the antibodies in the cells; thus, ANA testing is sometimes referred to as fluorescent antinuclear antibody test (FANA). The presence of ANA antibodies can indicate autoimmune disorders, such as systemic lupus erythematosus, rheumatoid arthritis, and Sjögren’s syndrome, among others. However, a positive ANA test does not confirm a specific diagnosis, as it can also occur in healthy individuals or those with certain infections and other conditions. Interpretation of the results requires careful consideration of clinical symptoms and additional diagnostic tests.

The test is valuable in guiding further investigation and helping health care providers develop appropriate treatment plans for patients exhibiting signs of autoimmune disease.

The ANA test is a sensitive screening test used to detect autoimmune diseases. Autoimmune diseases feature a misdirected immune system, and each of them has characteristic clinical manifestations that are used to make the precise diagnosis. The interpretation or identification of a positive ANA test (“ANA positive”) does not make a diagnosis. It simply suggests to the doctor to consider the possibility that an autoimmune disease is present.

When interpreting ANA test results, doctors typically look at the titer level and the staining pattern under a microscope. A higher titer, such as 1:160 or above, may indicate a greater likelihood of an autoimmune condition, while lower titers, like 1:40, can be found in healthy individuals or those with non-autoimmune issues. The specific fluorescence pattern can also help identify the type of autoimmune disease, as different conditions have distinct staining patterns.

It's important to recognize that a positive ANA test can occur in various situations, including chronic infections, malignancies, and even in healthy individuals. Therefore, the ANA test is not definitive on its own; it should be interpreted alongside clinical symptoms, patient history, and possibly other laboratory tests to achieve an accurate diagnosis. This holistic approach helps ensure the ANA test is a useful tool in diagnosing and managing autoimmune disorders.

A positive ANA test is reported as a titer, indicating the concentration of antibodies in the blood, expressed as a ratio (for example, 1:40, 1:80, 1:160). Generally, a titer of 1:40 or higher is considered positive, but the exact cutoff to call a test positive may vary among laboratories.

In addition to the titer, the test may also report the localization pattern for the antibody observed under a microscope, which can provide insights into potential autoimmune conditions. Common patterns include homogeneous, speckled, and nucleolar, each associated with different diseases.

It's important to note that a positive ANA test does not definitively indicate a specific diagnosis, as it can also be found in healthy individuals and various other conditions, including infections and malignancies. Therefore, interpreting a positive ANA result should always be done in conjunction with clinical findings and additional diagnostic tests.

The normal ANA level is typically defined as a titer of 1:40 or lower, although specific reference ranges and cutoffs can vary among laboratories. A titer of 1:40 means that antibodies can be detected when the blood is diluted 40 times. Levels above this threshold are generally considered positive and may warrant further investigation.

In addition to the titer, the presence of specific patterns observed under a microscope that reveal the precise localization of the antibody can also provide important context. Some patterns may be more indicative of autoimmune diseases than others. However, it is essential to understand that a normal ANA result does not completely rule out the possibility of an autoimmune disorder; clinical evaluation and additional testing are necessary for a comprehensive assessment.

ANAs can be produced in patients with the following conditions:

• infections (virus or bacteria),
• lung diseases (primary pulmonary fibrosis,
• pulmonary hypertension),
• gastrointestinal diseases (ulcerative colitis, Crohn's disease, primary biliary cirrhosis, alcoholic liver disease),
• hormonal diseases (Hashimoto's autoimmune thyroiditis, Grave's disease),
• blood diseases (idiopathic thrombocytopenic purpura, hemolytic anemia),
• cancers (melanoma, breast, lung, kidney, ovarian, and others),
• skin diseases (psoriasis, pemphigus), 
• as well as in the elderly and
• those people with a family history of rheumatic diseases.

The presence of ANAs in these non-autoimmune conditions highlights the complexity of the immune response and the potential for cross-reactivity. For example, chronic infections can stimulate the immune system to produce ANAs, complicating ANA test interpretation. Similarly, certain cancers may trigger an immune response that results in positive ANA test results.

The ANA test may also yield positive results in patients undergoing treatment for other conditions, as some medications can induce the formation of ANAs. ANAs can also be detected in hormonal diseases like Hashimoto's thyroiditis and Graves' disease, which are primarily autoimmune in origin.

Ultimately, the presence of ANAs in non-autoimmune conditions necessitates careful interpretation of the ANA test results within the broader clinical context. This approach enables healthcare providers to differentiate between true autoimmune diseases and other conditions that may produce antinuclear antibodies, facilitating accurate diagnosis and management.

A positive ANA test can sometimes be seen in the context of infections, particularly those that trigger an immune response similar to that observed in autoimmune diseases. Some infections known to cause a positive ANA include:

• Viral infections: Certain viruses, such as Epstein-Barr virus (EBV), cytomegalovirus (CMV), and hepatitis C virus (HCV), have been associated with positive ANA results. These viruses can stimulate the immune system, leading to the production of autoantibodies. These infections can trigger immune dysregulation that mimics autoimmune disease processes.
• Bacterial infections: Chronic bacterial infections, such as those caused by syphilis, tuberculosis, or certain strains of Mycoplasma or Chlamydia, may also result in positive ANA tests. The immune response to these infections can overlap with autoimmune processes.
• Parasitic infections: Certain parasitic infections, such as those caused by Schistosoma or Toxoplasma species, can induce a positive ANA test. The immune system's reaction to these parasites can mimic the mechanisms of autoimmune diseases.

While a positive ANA test can occur with these infections, it is crucial to note that it does not confirm an autoimmune disease. Clinical correlation and further testing are necessary to determine the underlying cause of a positive result.

Many medications can sometimes stimulate the production of ANAs, including

• procainamide (Procan SR),
• hydralazine (Apresoline), and
• phenytoin (Dilantin).

ANAs that are stimulated by medication are referred to as drug-induced ANAs. This does not necessarily mean that any disease is present when these ANAs are "induced." Sometimes diseases are associated with these ANAs, and they are referred to as drug-induced diseases. For instance, drug-induced lupus erythematosus is a well-known condition in which certain medications lead to the development of autoimmune-like symptoms along with positive ANA test results.

It is important to note that drug-induced ANAs can appear even after the medication is discontinued, as it may take time for the immune response to normalize. In these cases, ANA test results can complicate diagnosis, as health care providers need to distinguish between true autoimmune disorders and temporary positive results due to medication exposure.

In clinical practice, the presence of drug-induced ANAs emphasizes the need for careful interpretation of ANA test results, especially in patients with a history of medication use that is known to cause such antibodies. This comprehensive approach helps in making informed decisions regarding further testing and potential treatment options.

ANAs present different "patterns" depending on the staining of the cell nucleus in the laboratory showing the localization of the antibody:

• homogeneous or diffuse pattern;
• speckled pattern;
• nucleolar pattern; and
• peripheral or rim pattern.

While these patterns are not specific to any one illness, certain illnesses can more frequently be associated with one pattern or another. The patterns can sometimes give the doctor further clues as to the types of illnesses to look for in evaluating a patient. For example, the nucleolar pattern is more commonly seen in the disease scleroderma, while the homogeneous pattern is often associated with systemic lupus erythematosus (SLE). The ANA speckled pattern, on the other hand, is seen in many conditions including Sjögren's syndrome and mixed connective tissue disease, and in people who do not have any autoimmune disease. These patterns are determined by technical experts who routinely interpret the ANA lab tests.

Understanding the patterns of ANAs can significantly enhance diagnostic accuracy. However, health care professionals must remember that while certain patterns may correlate with specific autoimmune diseases, they are not definitive indicators on their own. Therefore, the ANA test results, including the observed patterns, should always be considered in conjunction with the patient's clinical history, symptoms, and additional laboratory findings for a comprehensive assessment.

No. ANAs can be found in approximately 5% of the normal population, usually in low titers (low levels). These people usually have no disease.

• Titers of 1:80 or lower are less likely to be significant. (ANA titers of less than or equal to 1:40 are considered negative.)
• Even higher titers are often insignificant in patients over 60 years of age. The normal range for antinuclear antibodies can vary slightly depending on the laboratory and the methods used, but typically, a titer of 1:40 or lower is deemed normal. Higher titers, especially those above 1:160, may warrant further investigation, as they can be indicative of autoimmune diseases but do not confirm a diagnosis on their own. Ultimately, the ANA result must be interpreted in the specific context of an individual patient's symptoms, underlying medical conditions, and other test results. The ANA test is a sensitive screening tool, and its significance can vary widely. It may or may not be significant, even if positive, in a given individual. Therefore, health care providers must consider the full clinical picture, including the presence or absence of symptoms suggestive of autoimmune disease, when evaluating ANA test results. This holistic approach ensures that patients receive appropriate follow-up and care based on their unique health circumstances.

• What does it mean when your ANA is positive? A positive ANA test suggests the presence of autoantibodies, which can be associated with autoimmune diseases such as lupus, Sjögren's syndrome, juvenile arthritis, polymyositis, dermatomyositis, and scleroderma. It is important to note that a positive result is not definitive for any specific condition and can also occur in healthy individuals. Further diagnostic testing and clinical correlation are essential for an accurate diagnosis.
• Can ANA positive be cured? A positive ANA test is not a disease and cannot be "cured." It is a marker indicating the presence of autoantibodies due to an underlying autoimmune condition. While treatments can help manage symptoms and improve quality of life for conditions associated with a positive ANA, such as lupus or rheumatoid arthritis, these conditions typically require ongoing management rather than a complete cure. Regular monitoring and appropriate therapy are essential for controlling disease activity.