Blood Test for Autoimmune Disorders

Autoimmune diseases refer to a condition where a body’s immune system reacts against its tissues, leading to various disorders. But here’s the thing: How are autoimmune disorders diagnosed? What is the blood test for autoimmune diseases? It turns out that the diagnosis and identification of these disorders are not straightforward.

Depending on the type of disease, more than one test may be required to confirm the presence of an autoimmune disorder. Sometimes, even after multiple tests, expert opinions are called upon for further investigation.

Let’s explore the top 10 lab tests for autoimmune diseases, how diagnosis works, and specific details of antibodies related to different disorders in this blog post.

Top 10 Blood Tests for Autoimmune Diseases

1. ANA Test
2. Rheumatoid Factor (RF)
3. Anti-CCP Test
4. Anti-dsDNA Test
5. ENA Panel
6. SCL-70 & Anti-Centromere Antibodies
7. ANCA Antibodies
8. Myositis Panel
9. Complement Levels
10. Inflammatory Markers (ESR & CRP)

ANA Test

The ANA (Antinuclear Antibody) test is often termed the introductory test for determining autoimmune diseases. It is a blood test for autoimmune disease that identifies specific antibodies targeting the nucleus of body cells. The presence of such antibodies indicates the onset or existence of autoimmune disorders. However, a positive result in the test is not a direct indication. Other tests are required to confirm the same. Even normal people sometimes get a positive result.

The presence of such antibodies can also be caused by the following conditions:

• Chronic infections, like Hepatitis B, C, and HIV.
• Certain acne medications, antibiotics, and antihypertensive medications cause a positive ANA.
• Exposure to radiation or radiation therapy.
• Previous history of cancers or lymphoma can trigger such antibodies.

Rheumatoid Factor (RF)

The Rheumatoid Factor test determines an autoantibody responsible for Rheumatoid arthritis. The same RF autoantibody is also associated with juvenile arthritis, lupus, TB, and some cancers, like leukaemia.

The RF test is not always helpful in diagnosing Rheumatoid arthritis because at least 20% of people with the condition do not have the autoantibody. In such cases, Rheumatoid arthritis is confirmed by comparing RF and anti-CCP test results.

Anti-CCP Test

As indicated previously, anti-CCP tests are yet another determinant of Rheumatoid arthritis. Anti-CCP or Anti-cyclic citrullinated peptide is another autoantibody associated with the autoimmune disease. Though this autoantibody is specific to Rheumatoid arthritis, it is not as reliable in confirming the condition.

Three of every 10 tests will likely return a false negative result. But a positive result is 96% accurate. It is combined with the RF test to confirm this autoimmune disease.

Anti-dsDNA Test

Anti-dsDNA (anti-double-stranded DNA) antibodies are specific to systemic lupus erythematosus (SLE), an autoimmune disease. They target double-stranded DNA but can also appear in other autoimmune conditions or due to certain medications. Anti-dsDNA blood tests for autoimmune diseases are almost definitive tests.

The presence of anti-dsDNA antibodies in the blood is a key feature of SLE diagnosis. Monitoring these antibodies is crucial for assessing disease activity. Elevated levels can indicate active lupus, which may lead to organ damage, especially in the kidneys. Regular monitoring, along with other tests, is essential for managing SLE.

ENA Panel

The ENA, or anti-extractable nuclear antigen test, aims to determine several autoantibodies: Smith (Sm) antigen, ribonuclear protein (RNP) or U1RNP, anti-SSA (Ro), and anti-SSB (La). The presence of any of these antibodies indicates lupus. ENA is a complete panel blood test for autoimmune disease, similar to the Complete Blood Count panel. Confirmation of the autoimmune condition can only be made after detecting all the autoantibodies.

SCL-70 & Anti-Centromere Antibodies

SCL-70 (or anti-topoisomerase I) and anti-centromere antibodies are types of autoantibodies linked to scleroderma, an autoimmune disease causing skin thickening and organ involvement. Both have a role in triggering different types of systemic sclerosis, an autoimmune condition affecting the skin and lungs and showing other severe symptoms.

Once again, this blood test for autoimmune disease is not definitive—having these antibodies doesn’t confirm a diagnosis; specialists trained in autoimmune diseases are needed for a definitive diagnosis.

ANCA Antibodies

ANCA (anti-neutrophil cytoplasmic antibodies) are autoantibodies that target components in the cytoplasm of neutrophils, a type of white blood cell involved in immunity. They're linked to ANCA-associated vasculitis (AAV), which includes severe conditions like GPA, MPA, and EGPA. These diseases cause blood vessel inflammation, damaging organs like the skin, kidneys, heart, lungs, and GI tract.

There are two main types of ANCA antibodies: Cytoplasmic ANCA (c-ANCA) and Perinuclear ANCA (p-ANCA). While detecting these antibodies is a cause of concern, it is not the only blood test for autoimmune disease. Expert opinions from rheumatologists or nephrologists, along with consideration of other factors, are required for complete diagnosis.

Myositis Panel

A myositis panel is a blood test for autoimmune diseases known as a myositis antibody panel. It helps diagnose and classify inflammatory muscle diseases like polymyositis or dermatomyositis. These diseases cause muscle inflammation, weakness, pain, and fatigue. Myositis Panel detects specific antibodies:

• Anti-Jo-1: Linked to polymyositis and dermatomyositis with lung involvement.
• Anti-Mi-2: Specific to dermatomyositis and often related to skin symptoms.
• Anti-SRP: Associated with severe muscle weakness in polymyositis.
• Anti-MDA5 (anti-CADM-140): Found in dermatomyositis with specific skin and lung risks.

Complement Levels

Complements are vital proteins in the immune system, crucial for fighting infections and removing damaged cells. They work alongside antibodies and immune cells to enhance immune responses. Complements have three main functions: They mark pathogens for destruction by immune cells, regulate inflammation, and directly destroy pathogens.

Testing complement levels like C3, C4, and CD5 is a common blood test for autoimmune diseases. They can indicate if diseases like lupus are active. Complement levels decrease, especially during autoimmune disease conditions. Monitoring these levels, along with other markers like anti-dsDNA antibodies, can help manage conditions like lupus. Complement levels can also decrease in kidney-affecting vasculitis, such as Goodpasture syndrome.

Inflammatory Markers (ESR & CRP)
In autoimmune diseases, doctors often use two key markers to track inflammation: ESR and CRP. ESR (Erythrocyte Sedimentation Rate) measures how quickly red blood cells settle. ESR rate increases during inflammation when proteins cause them to clump. But it’s only a general blood test for autoimmune diseases that doesn't pinpoint the cause.

There is another protein, CRP (C-reactive protein). It is produced by the liver in response to inflammation and rises rapidly during acute inflammation, so CRP is considered more specific. Both of the autoimmune blood tests provide valuable information about inflammation severity and are used in various conditions, including infections, autoimmune diseases, and certain cancers.

Inflammatory Markers (ESR & CRP)

In autoimmune diseases, doctors often use two key markers to track inflammation: ESR and CRP. ESR (Erythrocyte Sedimentation Rate) measures how quickly red blood cells settle. ESR rate increases during inflammation when proteins cause them to clump. But it’s only a general blood test for autoimmune diseases that doesn't pinpoint the cause.

There is another protein, CRP (C-reactive protein). It is produced by the liver in response to inflammation and rises rapidly during acute inflammation, so CRP is considered more specific. Both of the autoimmune blood tests provide valuable information about inflammation severity and are used in various conditions, including infections, autoimmune diseases, and certain cancers.

Autoimmune Symptom Checklist

• Fatigue
• Skin related problems
• Joint pain and swelling
• Abdominal pain or digestive issues
• Recurring fever
• Swollen glands
• Morning Stiffness
• Brain Fog

Conclusion

Understanding the top autoimmune disease blood tests can empower patients and practitioners to overcome these complex diseases more effectively. From ANA and anti-dsDNA to complement levels and inflammatory markers, each test offers critical insights. By staying informed and working closely with healthcare professionals, patients can achieve better disease management and a higher quality of life. Knowledge is your strongest ally in the fight against autoimmune disorders, more than anything.