Have you ever wondered how doctors identify autoimmune diseases? What if I told you ten essential tests help unravel the mystery behind these conditions? In this article, I’ll explore the fascinating world of autoimmune diseases and discuss the key diagnostic blood tests autoimmune disease I use to uncover them.
What are Autoimmune Diseases?
Picture this: your immune system is like a superhero defending your body against harmful invaders. But what if it gets confused and starts attacking your cells instead?
That’s what happens in autoimmune diseases.
These conditions can affect various organs and tissues, leading to a range of perplexing symptoms. It often takes months to years until the symptoms slowly develop, creating a lot of confusion. Many times patients see a lot of physicians before they reach a diagnosis.
I know it is frustrating and time-consuming. I know that you, the patient, feel frustrated that you know something is wrong with your body; you feel it, but unfortunately, the doctors cannot see it.
However, some blood tests for autoimmune disease were specifically developed to diagnose different types of autoimmune diseases.
This article will introduce you to ten incredible blood tests for autoimmune disease to help solve your medical puzzle.
Not all patients need these blood tests for autoimmune disease, so it is important to discuss them with your physician and decide if these blood tests for autoimmune disease can be helpful for you.
#1 The ANA Test: Unmasking the Culprit
Meet the ANA (anti-nuclear antibody) test, I call this the intro test into the autoimmune diseases world. Many patients are referred to me or called to be seen when they have a positive ANA test.
This blood test for autoimmune disease searches for unique antibodies that target the nucleus of your cells. By identifying these antinuclear antibodies, doctors can uncover autoimmune diseases.
!!! However, please take a deep breath and do not think that if your ANA test is positive, you have lupus or another autoimmune disease.
You need more than this test.
In my YouTube channel, I discuss the ANA test more in-depth and in which conditions you can develop a positive ANA test.
Just to name a few other possibilities for a positive ANA test:
- Chronic infections, like Hepatitis B, C, HIV or
- Medications like acne medications, some antibiotics, some antihypertensive medications
- Exposure to radiation or radiation therapy
- Prior history of cancers or lymphoma
- Even in normal people, we do see positive ANA tests.
So, before you jump on Dr. Google, call your doctor or Rheumatologist OnCall to be evaluated further!
#2 Rheumatoid factor (RF) – Unveiling Arthritis’s Secrets
When patients get tested with this test: Rheumatoid factor or RF, as we call it…..the reason is usually to be evaluated for arthritis.
Have you heard of rheumatoid arthritis?
It’s like a sneaky villain attacking your joints, especially the small joints in the hands and feet. This test looks for antibodies that target a specific part of your immune system. When these antibodies are present, it strongly indicates that rheumatoid arthritis might be lurking.
However, a positive rheumatoid factor test ALONE will not make the diagnosis!
Do you need clarification?
Let me explain to you!
A positive RF test indicates that you have a lot of inflammation in the body that can come from Rheumatoid arthritis, but it may also come from an infection, like hepatitis C.
In fact, only 60-80% of people with Rheumatoid arthritis have a positive RF test. So again, it is important to look at all the aspects and signs and symptoms, not only at this test.
#3 Anti-CCP Test (anti-cyclic citrullinated peptide antibodies)
Are you ready for another clue in the case of rheumatoid arthritis?
Anti-CCP (anti-cyclic citrullinated peptide) antibodies are autoantibodies that are commonly associated with rheumatoid arthritis (RA). These antibodies target citrullinated peptides, modified protein fragments found in the joints of individuals with RA. The presence of anti-CCP antibodies in the blood is considered a specific marker for rheumatoid arthritis and can aid in the diagnosis and prognosis of the condition.
Why?
Anti-CCP antibodies are associated with more severe disease and increased risk of joint damage, affecting other organs like the heart, lungs, or the eyes and sometimes poor response to treatment.
#4 Anti-dsDNA (anti-double-stranded DNA antibodies) Test: A Window into Lupus
Anti-dsDNA (anti-double-stranded DNA) antibodies are autoantibodies that target double-stranded DNA, which is the genetic material found in the nucleus of cells. These antibodies are specific to systemic lupus erythematosus (SLE), a complex autoimmune disease. However, these antibodies can also be seen in other autoimmune diseases or induced by certain medications (e.g., blood pressure medications, antibiotics).
The presence of anti-dsDNA antibodies in the blood is considered a hallmark feature of systemic lupus erythematosus (SLE) and is included in the diagnostic criteria for the disease.
Suppose you are diagnosed with lupus, based on this blood test for autoimmune disease and many other criteria that are needed for diagnosis. In that case, these antibodies need to be monitored periodically as they can indicate that your disease is becoming active.
If the titer of dsDNA autoantibodies increases, this indicates that the lupus is active and can potentially damage your organs like the lung, heart, kidneys, and brain.
Especially for people with kidney involvement, the anti -dsDNA antibodies must be monitored at least every 3 months, along with other tests like your cell counts, comprehensive metabolic panel, complement levels, and urine analysis.
#5 The ENA (anti-extractable nuclear antigen) Panel: Unraveling Autoimmune Mysteries
Anti-extractable nuclear antigen (anti-ENA) panel consists of multiple autoantibodies, including Smith (Sm) antigen, ribonuclear protein (RNP) or U1RNP, anti-SSA (Ro), and anti-SSB (La).
The Sm antigen or anti-Smith antibodies are highly specific for Systemic lupus, but it is found only in ∼25% of SLE patients.
The U1RNP antigen is seen in patients with Systemic lupus, systemic sclerosis, and in patients with mixed connective tissue disease, but it is not specific to only one of these diseases.
Now, patients with only this antibody positive and none of the others might have mixed connective disease, but again, you need other signs and symptoms to have this diagnosis.
The SSA (Ro) and SSB (La) nuclear antigens are often found together in those patients with Sjögren’s syndrome, but they can also be seen in some patients with lupus. If you want to learn more about these antibodies and Sjögren’s syndrome, check out my channel, where you will find many videos to get you educated.
#6: SCL-70 (anti-topoisomerase I) and anti-centromere antibodies
SCL-70 (also known as anti-topoisomerase I) and anti-centromere antibodies are two specific types of autoantibodies associated with systemic or limited forms of sclerosis or scleroderma, another type of autoimmune disease.
SCL-70 Antibodies
These autoantibodies target a protein called topoisomerase I, which is involved in DNA replication and repair. These antibodies are primarily associated with systemic sclerosis, also known as scleroderma. Systemic sclerosis is a chronic autoimmune disease characterized by fibrosis (thickening) of the skin and involvement of internal organs, especially the lungs, Gastrointestinal tract, and even heart.
The presence of SCL-70 antibodies in the blood is considered a specific marker for systemic sclerosis, particularly the diffuse cutaneous systemic sclerosis subset.
These antibodies are often associated with more severe disease manifestations, such as widespread skin involvement and lung fibrosis.
Anti-Centromere Antibodies
These types of autoantibodies target proteins found in the centromeres of chromosomes. These antibodies are primarily associated with a subtype of systemic sclerosis called limited cutaneous systemic sclerosis (formerly known as CREST syndrome).
Limited cutaneous systemic sclerosis typically presents with skin involvement limited to the hands, face, and lower arms, as well as other distinctive features like calcinosis (which are deposits of calcium in the skin), Raynaud’s phenomenon, esophageal dysfunction or heartburns, sclerodactyly (which refers of thickening of your skin on the fingers), and telangiectasia (which refers to some capillary dilatations on the skin or your tongue).
Anti-centromere antibodies in the blood are highly specific to limited cutaneous systemic sclerosis. Still, it can be seen in autoimmune liver diseases like primary biliary cirrhosis and even in patients with lupus.
Again, I cannot stress enough that a positive blood test for autoimmune disease will not make the diagnosis, and you need a specialist like me or others trained in recognizing autoimmune diseases to make the final call.
#7 ANCA (anti-neutrophil cytoplasmic) antibodies
ANCA (anti-neutrophil cytoplasmic antibodies) are a group of autoantibodies that target certain components within the cytoplasm of neutrophils, a type of white blood cell involved in the immune response.
ANCA antibodies are associated with a group of autoimmune diseases called ANCA-associated vasculitis (AAV).
There are three types of ANCA-associated vasculitis
- Granulomatosis with polyangiitis (GPA, formerly known as Wegener’s granulomatosis)
- Microscopic polyangiitis (MPA)
- Eosinophilic granulomatosis with polyangiitis (EGPA, formerly known as Churg-Strauss syndrome).
These types of autoimmune diseases are characterized by inflammation of blood vessels, resulting in damage to various organs and tissues from skin to kidneys, heart, lungs to gastrointestinal tract. These are very serious conditions, and usually, people are very sick.
ANCA antibodies can be divided into two main types based on the staining patterns observed in laboratory tests:
Cytoplasmic ANCA (c-ANCA): c-ANCA antibodies are directed against an enzyme called proteinase 3 (PR3) present in the cytoplasm of neutrophils. c-ANCA is strongly associated with GPA.
Perinuclear ANCA (p-ANCA): p-ANCA antibodies are typically directed against an enzyme called myeloperoxidase (MPO) found in the perinuclear region of neutrophils. p-ANCA is commonly associated with MPA and EGPA.
It’s important to note that ANCA antibodies can also be found in other conditions like chronic infections, people that use cocaine or can also be induced by medication, so they are not solely limited to ANCA-associated vasculitis.
Therefore, the interpretation of ANCA testing results should be done together with your other clinical symptoms, imaging studies, and always by rheumatology experts or a kidney specialist or nephrologist who can be involved in treating these diseases.
#8 Myositis panel
A myositis panel, also known as an autoimmune myositis antibody panel or myositis-specific antibody panel, is a group of laboratory tests that help diagnose and classify inflammatory muscle diseases known as myositis: polymyositis or dermatomyositis.
Polymyositis is an autoimmune disease characterized by inflammation of the muscles, leading to muscle weakness, pain, and fatigue. Dermatomyositis involves both the muscles and the skin, causing specific rashes for this disease.
The myositis panel typically includes several specific autoantibody tests, and I will discuss a few of them here:
- Anti-Jo-1 antibody: Associated with polymyositis (PM) and dermatomyositis (DM) with lung involvement.
- Anti-Mi-2 antibody: Specific to dermatomyositis and often associated with skin manifestations.
- Anti-SRP antibody: Associated with a subset of polymyositis characterized by severe muscle weakness and increased risk of muscle damage.
- Anti-MDA5 (anti-CADM-140) antibody: Seen in a subset of dermatomyositis patients with specific skin findings and risk of lung involvement.
#9 Complement levels
Complements are a group of proteins that play a crucial role in the immune system’s defense against infections and the removal of damaged cells, and they can form immune complexes.
They are an integral part of the innate immune response, which is the body’s immediate defense mechanism against pathogens.
Complements work in coordination with other immune system components, such as antibodies and immune cells, to enhance the immune response. They have three main functions:
- Complements can coat pathogens, marking them for recognition and destruction by immune cells like macrophages and neutrophils. This process is called opsonization.
- Complements can trigger and regulate inflammation, a critical response that helps recruit immune cells to the infection or tissue damage site.
- Complements can directly destroy certain pathogens, particularly bacteria, through the membrane attack complex (MAC). The MAC forms a pore-like structure on the bacteria’s surface, disrupting the membrane and then cell lysis or destruction.
We can measure different components of the complement system like C3, C4, and CD5, and they can tell us if a disease like lupus is active or not. Usually in patients with active lupus, the levels of C3, C4 is low are they are consumed in the autoimmune process. If you remember what I said about anti-dsDNA antibodies, then monitoring C3 and C4 and anti-dsDNA antibodies every 3 months can tell us if the lupus is controlled.
Complements levels can also decrease in certain types of vasculitis that can affect the kidneys, like Goodpasture syndrome.
#10: Inflammatory Markers
Have you ever heard the saying, “Where there’s smoke, there’s fire”? Then look at these blood tests for autoimmune disease like the smoke coming from inflammation, that is the fire.
There are two markers of inflammation, and I, as a rheumatologist monitor very frequently in my patients with autoimmune diseases:
ESR and CRP
ESR (erythrocyte sedimentation rate) and CRP (C-reactive protein) are two common blood tests for autoimmune disease used to measure inflammation in the body. They are often ordered together and provide complementary information about the presence and severity of inflammation.
ESR (Erythrocyte Sedimentation Rate)
ESR measures how quickly red blood cells settle in a test tube over a specified period, usually 1-2 hours.
When there is inflammation in the body, certain proteins, such as fibrinogen and immunoglobulins, cause red blood cells to clump together, leading to a faster sedimentation rate.
ESR is a non-specific test and can be influenced by various factors, including age, gender, anemia, and other medical conditions. It is typically used as a screening tool to detect the presence of inflammation but does not provide information about the specific cause.
CRP (C-reactive protein)
CRP is a protein produced by your liver in response to inflammation. Its levels increase rapidly during acute inflammation, which is considered a more specific marker of inflammation than ESR. CRP levels can rise within a few hours of the inflammatory stimulus and can be used to monitor disease activity or response to treatment. It is commonly used to assess inflammation in various conditions, including infections, autoimmune diseases, and cardiovascular diseases.
Both ESR and CRP can be elevated in a wide range of conditions associated with inflammation, such as infections, autoimmune diseases (e.g., rheumatoid arthritis, lupus), vasculitis (here i want to stress the importance of an elevated ESR in patients with giant cell arteritis or polymyalgia rheumatica) but also some cancers.
Conclusion
We’ve journeyed through the ten most common tests that we use to diagnose autoimmune diseases! From the ANA test, different types of autoantibodies, ANCA antibodies to Rheumatoid factor, anti-CCP antibodies, to the myositis panel, complement levels, and markers of inflammation!!!!
Remember, if you suspect you have an autoimmune condition, do not consult DR. Google or do not take advice from people on social media or so-called “Autoimmune experts”! Find an experienced physician who diagnoses and treats people with autoimmune diseases daily!
Make your research and find a specialist who can help you decipher your diagnosis, someone who will take time and make a true effort to help you!
Through my company, Rheumatologist OnCall, I have been able to help many patients that were wondering if they have or not an autoimmune disease in many US states. If you need help , don’t hesitate to check out my website and if needed, schedule an appointment from the comfort of your home.
