The ANA test detects antinuclear antibodies in the blood, which can indicate autoimmunity. It is commonly used to diagnose lupus and other autoimmune disorders. ANA patterns can also provide insight into certain diseases, but are not specific to any one condition. ANAs can also be present in patients without autoimmune diseases, and can be drug-induced.
An ANA test, also known as an antinuclear antibody test, is designed to detect antinuclear antibodies in a blood sample. The acronym ANA refers to antinuclear antibodies which are automatic in the sense that they automatically bind to certain surfaces within the nucleus of cells. While a healthy person should possess a certain amount of antibodies to protect themselves from invading bacteria, antinuclear antibodies work against this self-defense mechanism. Indeed, a high level of antinuclear antibodies present may indicate that the immune system is capable of mistakenly launching an attack on healthy tissue. This condition is known as autoimmunity.
The ANA test was developed by Dr. George Friou in 1957 to help diagnose autoimmune disorders. Most commonly, an ANA test is done when lupus is suspected. However, your doctor may order an ANA test to rule out various other autoimmune disorders when certain symptoms are present, such as frequent joint pain, skin rashes, chronic fatigue, or a persistent low-grade fever. Additional blood tests may be done in addition to the ANA test, to include erythrocyte sedimentation rate (ESR) and/or C-reactive protein (CRP) tests. Often, the results of each blood test can be determined from a single serum sample.
ANA tests allow the doctor to examine how some antibodies react to the cell nucleus in vitro. When a reaction is observed, it is said to be antinuclear antibodies. Sometimes, it is necessary to use fluorescence instruments to determine if there is an antinuclear reaction. For this reason, the ANA test is sometimes called a fluorescent antinuclear antibody test, or FANA.
Antinuclear antibodies, or ANAs, can also be present in patients without autoimmune diseases. For example, ANAs can be detected in those with kidney, liver, breast, or other types of cancer. ANAs can also be found in people with chronic infectious diseases. Also, a positive ANA test result can occur in people with Crohn’s disease, Grave’s disease, ulcerative colitis, Addison’s disease, rheumatoid arthritis, and many other disorders. Additionally, approximately five percent of the population exhibit low levels of ANA with no disease present.
A positive ANA test result can also be drug-induced. For example, procainamide, dilantin and hydralazine are drugs known to promote the production of ANA. In this case, elevated ANA levels may not be related to any disease. However, if a disease is diagnosed, it is said to be a drug-induced disease.
In addition to determining the number of ANAs present during an ANA test, the doctor also looks at ANA patterns. Specifically, this observation depends on the type of staining used on the cell nucleus, which results in a homogeneous or diffuse, peripheral or hem, speckled or nucleolar pattern. No model is specific to a particular disease. However, some diseases are more commonly linked to certain patterns. For example, the nucleolar pattern is most commonly found in people with scleroderma.
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