The antinuclear antibody (ANA) test is one of the most common tests performed in rheumatology and is prescribed by most clinicians for patients suspected of having rheumatic immune disease, even in a portion of health checkups. The purpose is to provide laboratory evidence for the diagnosis of rheumatic diseases. However, many people who get the report and see a positive ANA (1:100, 1:320, etc.) can’t help but start to get nervous, thinking that they must have rheumatism. However, this is not absolute. There are many other conditions in which a positive ANA can occur. First, let’s understand what ANA is. As we all know, there are many components inside the cells of the human body, including the nucleus, cytoplasm, organelles (such as Golgi apparatus), and so on. As shown below: The human body has an immune system that defends against foreign enemies (e.g. bacteria, viruses). When an enemy comes, the human body produces antibodies to deal with the enemy, and these antibodies are beneficial to the person, and we call them protective antibodies. However, the body’s immune system sometimes accidentally produces antibodies against the body’s own tissue cells, which we call autoantibodies. If antibodies are produced against the nucleus of a cell, we call them anti-nuclear antibodies (ANA). These antibodies can be harmful to the person and are often the cause of autoimmune diseases (such as rheumatism). As research continues, we have found that the body produces antibodies not only against the nucleus, but also against cytoplasmic or organelle components. Therefore, we have now expanded the concept of ANA from the original nucleus to the whole cell, which is divided into five major categories: anti-DNA, anti-histone, anti-nuclear antibodies, and antibodies against other cellular components. The strength of anti-nuclear antibodies is expressed in titers ranging from 1:100 (some are smaller), 1:320, 1:1600, 1:3200, and so on. The higher the titer, the greater the likelihood of rheumatic disease. Antinuclear antibodies are very important for the diagnosis of rheumatic diseases and can help rheumatologists to better diagnose the disease. However, does a positive antinuclear antibody necessarily mean rheumatic disease? ANA positivity can have several possibilities: 1. Rheumatic immune diseases ANA positivity should really be considered as a rheumatic immune disease first, ANA positivity is most common in systemic lupus erythematosus and mixed connective tissue diseases. In other connective tissue diseases such as rheumatoid arthritis, scleroderma, dry syndrome, vasculitis, overlap syndrome and other rheumatic diseases can also appear positive. Also, the higher the ANA titer, the greater the correlation with autoimmune disease. At this time, it is often necessary to further check other autoantibody items, such as anti-CCP antibody for rheumatoid arthritis, anti-Sm antibody and anti-dsDNA antibody for systemic lupus erythematosus, and anti-SSA antibody and anti-SSB antibody for dry syndrome to further help the diagnosis. The rheumatologist will determine whether you have rheumatism or not based on your condition, clinical manifestations and relevant tests. The first is that you already have rheumatic disease with associated damage, such as systemic lupus erythematosus, and you already have hematologic damage or kidney damage or damage to other organs. Another situation is that it is not yet a rheumatic disease and is still in the latent stage of rheumatic disease, with the possibility of developing rheumatic disease later. For example, the appearance of dsDNA antibodies, anti-SSA antibodies, and anti-SSB antibodies can all appear in the first few years of the onset of SLE, while currently being only ANA positive and dsDNA positive without any organ tissue damage. Although there are no clinical symptoms, it is still necessary to be extra careful, pay more attention to the dynamic changes of your body, and it is essential to go to the rheumatology department for regular checkups and seek help from your doctor. Especially for those patients with high titers. 2. Healthy people A study was conducted on the positive rate of ANA in healthy people, and it was found that no matter men, women and children, some of the healthy people were detected to be ANA positive, and the positive rate in women was higher than men, and the proportion of elderly, adolescent women and menopausal women seemed to be higher. Most of the ANA positivity in healthy individuals was predominantly low titer, such as 1:100 or 1:320, with few high titers. People in the latent stage of rheumatic disease mentioned above can also be considered healthy because they do not have rheumatic disease at the time of ANA testing. Therefore, healthy people should be tracked and followed up even if they are positive for ANA. 3. Tumors Autoantibodies can be detected in many tumor patients, such as breast cancer, lung cancer, nasopharyngeal cancer, liver cancer, esophageal cancer, etc. Autoantibodies may appear in the early stage of tumors. Immune response plays an important role in the production of autoantibodies, which may be an immune surveillance of the body and may be involved in killing and clearing mutated cells and inhibiting the growth of malignant tumors. Autoantibodies are generally not used in the diagnosis of tumor, but tumor patients detected autoantibodies, the first thing to consider is whether it is produced by the tumor itself, not caused by rheumatism. 4. Hepatitis B China is a large country with hepatitis B. Patients with chronic viral hepatitis have autoimmune phenomenon and autoantibodies can be detected in the serum. Some literature reports that the positive rate of total serum ANA in patients with HBV infection is about 30%, but mostly low titers (1:100) are predominant, and high titers are rare. It is generally believed that hepatitis B is accompanied by autoimmune phenomena, and low titers of autoantibodies only reflect the presence of antibodies to autoimmune reactions or disease states and do not directly affect immune function. If high titers are present, they may be closely related to autoimmune diseases. 5. Other diseases ANA positivity can also appear in tuberculosis, myasthenia gravis, thyroid disease, other infections and other diseases, but most of them are low titers. In summary, ANA positivity is not always rheumatic disease. Attention should be paid to exclude other diseases, and close follow-up and regular checkups are also required.