Table of ContentsView AllTable of ContentsCRP TestESR TestANA TestFerritin TestAnti-CCP TestRF TestIgA TestRoutine Blood TestsLess Common Tests
Table of ContentsView All
View All
Table of Contents
CRP Test
ESR Test
ANA Test
Ferritin Test
Anti-CCP Test
RF Test
IgA Test
Routine Blood Tests
Less Common Tests
There are different autoimmune blood tests that aid in the diagnosis ofautoimmune diseases. Autoimmune diseases are those in which theimmune systemattacks normal cells and tissues withinflammation.
Some of the most common autoimmune diseases include:
Some of these tests detect signs of inflammation or increases in proteins (likeferritin) that are hallmarks of autoimmunity. Other detect substances calledautoantibodiesthat direct the immune assault. There is no single test that can diagnose the over 80 types of autoimmune diseases.
This article describes the various blood tests that may be ordered to help diagnose an autoimmune disease. It explains how they are interpreted and what information each can provide.
Verywell / Michela Buttignol
C-Reactive Protein (CRP)
Increased CRP levels can provide evidence of inflammation that commonly occurs with autoimmune diseases as well as infections, cancer, and other diseases.The CRP is important because the absence of inflammation could exclude autoimmunity as a cause.
Interpretation of CRP levels is as follows:
Erythrocyte Sedimentation Rate (ESR)
Theerythrocyte sedimentation rate (ESR)test measures how quicklyerythrocytes(red blood cells) collect at the bottom of a test tube. Normally, RBCs settle slowly. A faster-than-normal rate generally indicates inflammation in the body.
The normal range for ESR measured in millimeters per hour (mm/hr) is:
As with the CRP test, a high ESR could indicate an autoimmune disease or other inflammatory conditions. On the flip side, a normal ESR may be an indication that autoimmunity is not involved.
Red Blood Cell Count: Understanding MCV, MCH, RDW, and More
Antinuclear Antibodies (ANA)
Antinuclear antibody (ANA) is one type of autoantibody that attacks the nucleus (center) of cells.
TheANA testis primarily used to diagnose lupus but may also indicate other autoimmune diseases like rheumatoid arthritis, scleroderma, or Sjögren’s disease.
An ANA result is negative or positive based on the concentration of the autoantibodies in a sample of blood (referred to as the titer). Titers are reported in ratios, most often 1:40, 1:80, 1:160, 1:320, and 1:640. Some, but not all labs will report a titer of 1:160 as positive.
A negative ANA test means no autoantibodies were detected and generally excludes autoimmunity as a cause. However, a positive ANA test doesn’t necessarily indicate an autoimmune disease. Up to 15% of people can have a positive low-titer ANA without any autoimmune disease.
ANA Accuracy in Diagnosing LupusAbout 95% of people with lupus have a positive ANA test result. Your healthcare provider may order the test if you have signs of lupus, including a butterfly-shaped rash on the cheeks and nose, hair loss, mouth or nose sores, and fingers that turn white or blue when cold or stressed (Raynaud’s syndrome).
ANA Accuracy in Diagnosing Lupus
About 95% of people with lupus have a positive ANA test result. Your healthcare provider may order the test if you have signs of lupus, including a butterfly-shaped rash on the cheeks and nose, hair loss, mouth or nose sores, and fingers that turn white or blue when cold or stressed (Raynaud’s syndrome).
How Lupus Is Diagnosed
Ferritin
With autoimmunity, autoantibodies can sometimes destroy red blood cells, causing them to release excess iron in the bloodstream. This excessive release of iron can overwhelm the body’s storage capacity, causing the liver to secrete more ferritin in an effort to rein in the freely circulating mineral.
Normal ranges of ferritin measured in nanograms per milliliter of blood (ng/mL) include:
Anything over these values may be suggestive of an autoimmune disease.
How Anemia Is Diagnosed
Anti-Cyclic Citrullinated Peptide (Anti-CCP) Antibodies
Anti-cyclic citrullinated peptide(anti-CCP) antibodiesare another type of autoantibody associated with rheumatoid arthritis. While specific to rheumatoid arthritis, the anti-CCP test is not a particularly sensitive one.
With a sensitivity of roughly 70%, the test will return afalse-negative resultin three of every 10 tests. On the other hand, it has a specificity of 96%, meaning that a positive result is almost always diagnostic of rheumatoid arthritis.
Anti-CCP results are described as negative or positive based on international units per milliliter of blood (IU/mL):
The interpretation can vary from one lab to the next.
Rheumatoid Factor (RF)
Therheumatoid factor (RF) testdetects an autoantibody closely linked to rheumatoid arthritis. The RF autoantibody can also be found with other autoimmune diseases like juvenile arthritis and lupus as well as tuberculosis and certain cancers like leukemia.
RF results are described as negative or positive based either on the titer or IU/mL values:
Despite the RF test’s usefulness in diagnosing rheumatoid arthritis, around 20% of people with the disease have little or no RF in their blood.
What Is the ELISA Test?Theenzyme-linked immunosorbent assay (ELISA)—sometimes referred to as the EIA—is a technology used to detect antibodies. It can be engineered to detect not only specific antibodies but also specific autoantibodies. ELISA technology is what “powers” the ANA, RF, and anti-CCP antibody tests.
What Is the ELISA Test?
Theenzyme-linked immunosorbent assay (ELISA)—sometimes referred to as the EIA—is a technology used to detect antibodies. It can be engineered to detect not only specific antibodies but also specific autoantibodies. ELISA technology is what “powers” the ANA, RF, and anti-CCP antibody tests.
Immunoglobulin A (IgA)
Antibodies are also known asimmunoglobulins. There are three main types: immunoglobulin A (IgA), immunoglobulin G (IgG), and immunoglobulin M (IgM). Of the three, IgA—or specifically the lack of IgA—may indicate an autoimmune disease.
IgA is found in the nose, airways, digestive tract, ears, eyes, and vagina as well as saliva, tears, and blood. In total, between 10% and 15% of the antibodies in your body are IgA antibodies.
A small number of people do not make IgA antibodies, referred to asselective IgA deficiency. The cause of selective IgA deficiency is poorly understood but is largely thought to be inherited.
People with selective IgA deficiency are not only at higher risk of allergies and infections but are more likely to have autoimmune diseases like rheumatoid arthritis, lupus, celiac disease, or inflammatory bowel disease.
Selective IgA is diagnosed with animmunoglobulin blood testthat measures how much of each antibody type is found in your blood.
Selective IgA deficiency may be diagnosed when IgA falls significantly below these reference values. In some cases, there may be no IgA detected at all.
Routine blood work is also a big part of diagnosing autoimmune diseases. Some of the common blood tests your healthcare provider may order include:
Several other, more routine tests can detect inflammation, but abnormal levels in these tests may not necessarily be a sign of autoimmune disease, including:
A variety of issues can cause false positive or false negative tests. These include taking certain medications, recent acute illness, injury, recent surgery, and lab error. Interpretation of test results is done with consideration of your symptoms and overall health. Often, tests for autoimmune disease are repeated to see patterns over time—and a test result that doesn’t seem right will usually be repeated.
A/G Ratio: Measuring the Proteins Albumin and Globulin
Less Common Autoimmune Tests
To make a more accurate diagnosis, a number of blood tests target specific antibodies or autoimmune markers. Some specific antibody tests that your healthcare provider may recommend include:
Summary
Common blood tests used to diagnose autoimmune diseases may detect markers of autoimmunity (like the CRP, ESR, ferritin, and IgA tests) or autoantibodies associated with autoimmunity (like ANA, RF, and anti-CCP antibody tests).
There is no single blood test that can diagnose any autoimmune disease on its own.
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Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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UCSF Health.Fibrinogen blood test.
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