Antibodies are used to protect against infection or disease-causing agents. An antinuclear antibody (ANA) is an antibody that incorrectly binds with normal protein in a cell’s nucleus. People with autoimmune conditions like Lupus are more likely to have ANAs. The ANA test checks for antinuclear antibodies in the blood.
OVERVIEW
What are antinuclear antibodies?
An antibody is a protein that white blood cells (B cells) make. Antibodies protect the body from invaders, such as viruses and bacteria. Autoantibodies are formed when antibodies mistakenly recognize our “self” cells for being “foreign”.
Although most people have autoantibodies in some form, it is usually very low. When there are enough autoantibodies, inflammation (swelling) can start. This causes the immune system to attack our bodies (autoimmune disease).
An antinuclear antibody (ANA) is an antibody that incorrectly binds a normal protein in a cell’s nucleus. People with autoimmune conditions like systemic Lupus Erythematosus are more likely to have an ANA. These ANAs may also be found in people with other autoimmune conditions, including Sjogren’s syndrome. Dermatomyositis. Polymyositis. Scleroderma.
Not everyone with ANAs is affected by an autoimmune disease. For example, ANAs can be found in 10-15% of completely healthy children. They may be present briefly in intercurrent infections (an infection that occurs during another infection) or in patients taking certain anticonvulsants (for example, isoniazid and hydralazine).
TEST DETAILS
What is the procedure for testing for antinuclear antibodies?
The ANA test does not diagnose a condition but is used to indicate the possibility of an autoimmune disease.
A blood sample is taken from a vein to perform an ANA test. The blood is then sent to a laboratory for analysis.
The ELISA is one type of ANA test. This test involves the addition of antigens to the blood sample. These are proteins that bind to antibodies. The test will detect the antibodies for the antigen in the blood.
Laboratories will often use ELISA to screen for potential patients. However, they will also run another Fluorescent Antinuclear antibody (FANA) test, which confirms the results. FANA results can be reported in titers and the pattern of autoantibodies (homogeneous or speckled), etc. ).
The addition of saline (saltwater) to a plasma sample (the protein-rich liquid portion of blood) is a way to determine the tipper reading. A 1:40 mixture is, for example, one portion of plasma and 40 parts of saline. This mixture is known as a “titer.” After the mixture has been diluted (watered down), tubes are created of 1:180, 1:160 and 1:320 mixtures, respectively. A higher titer indicates a greater amount of ANAs.
What is the purpose of an antinuclear antibodies test?
An ANA test should not be performed during a routine doctor visit. The test should only be ordered if there is a strong possibility that a child’s symptoms may be caused by an ANA positive rheumatic disorder such as Lupus, Sjogren’s syndrome or mixed connective tissue diseases.
An ANA test should not ever be ordered as a screening test for nonspecific complaints, such as musculoskeletal pain or fever.
In children with juvenile idiopathic arthritis (JIA), the ANA test can also predict future events (a way to tell ahead of time). The ANA test cannot be used to diagnose JIA. A positive ANA test can increase the risk of developing uveitis (inflammation in the eyes). They will need more frequent eye examinations by an ophthalmologist than JIA patients with a negative ANA.
RESULTS and FOLLOW-UP
What should I do if my son or daughter has a positive ANA?
The ANA test will be interpreted by your physician or pediatric rheumatologist in conjunction with other laboratory studies, your child’s history, and a physical exam to determine any signs of ANA-related rheumatologic diseases. If the doctor suspects that your child may have a specific disease, further testing will be performed.
ANA testing is known for its high false-positive rate. Even people without an autoimmune condition can have higher ANA levels. Talking to your child’s paediatrician and pediatric rheumatologist is important to determine if a positive ANA test is valid or if it relates directly to your child’s symptoms.
