An autoimmune screen is a set of laboratory tests used to help diagnose autoimmune disorders, conditions in which the immune system mistakenly attacks the body’s own tissues. This screening helps to identify the presence of autoantibodies, which are proteins that the body produces against its own cells and tissues. Here’s an overview of typical tests that might be included in an autoimmune screen:
- Antinuclear Antibody Test (ANA)
- Purpose: Detects antibodies that bind to components of the nucleus of cells. It’s a primary test used to evaluate a person for autoimmune disorders.
- Common Use: Often used as an initial test to check for autoimmune diseases like lupus, scleroderma, Sjögren’s syndrome, and mixed connective tissue disease.
- Rheumatoid Factor (RF)
- Purpose: Measures the level of RF, which is an antibody found in people with rheumatoid arthritis.
- Common Use: Primarily associated with rheumatoid arthritis but can also be elevated in other autoimmune diseases and some infections.
- Anti-Cyclic Citrullinated Peptide Antibody (Anti-CCP)
- Purpose: More specific than RF for diagnosing rheumatoid arthritis. It detects antibodies against citrullinated peptides.
- Common Use: High specificity for rheumatoid arthritis, often appearing before symptoms start.
- Antibodies to Double-Stranded DNA (Anti-dsDNA)
- Purpose: Tests for antibodies against double-stranded DNA, a type of autoantibody primarily associated with lupus.
- Common Use: Highly specific for systemic lupus erythematosus (SLE).
- Extractable Nuclear Antigen Antibodies (ENA) Panel
- Purpose: Measures autoantibodies to several specific proteins within the cell nucleus. This panel includes tests for antibodies like anti-Sm, anti-RNP, anti-SSA/Ro, and anti-SSB/La.
- Common Use: Helps to diagnose and differentiate between various systemic autoimmune diseases.
- Complement Tests
- Purpose: Measures the levels of complement proteins in the blood. Complement is a group of proteins that contribute to immune responses, and their levels can be low in autoimmune diseases.
- Common Use: Useful in diagnosing and monitoring conditions like lupus, where complement levels can be depleted.
- Antineutrophil Cytoplasmic Antibodies (ANCA)
- Purpose: Detects antibodies that target neutrophil proteins.
- Common Use: Important for diagnosing vasculitis, such as Wegener’s granulomatosis (now known as granulomatosis with polyangiitis).
- Erythrocyte Sedimentation Rate (ESR) and C-Reactive Protein (CRP)
- Purpose: These are nonspecific tests that measure inflammation in the body.
- Common Use: Often used to assess and monitor inflammatory activity, though not specific to autoimmune disorders.
Usage Considerations
When an autoimmune disorder is suspected based on symptoms, these tests can be very helpful in the diagnostic process. However, it’s important to note that positive results in some of these tests may occur in conditions other than autoimmune diseases. Thus, test results should always be interpreted in the context of the individual’s clinical presentation and medical history. Regular monitoring and follow-up tests may also be required to manage diagnosed autoimmune conditions effectively.