Autoimmune diseases are those in which theimmune systemattacks normal cells and tissues withinflammation.
Other detect substances calledautoantibodiesthat direct the immune assault.
There is no single test that can diagnose the over 80 types of autoimmune diseases.
Verywell / Michela Buttignol
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.
Normally, RBCs settle slowly.
A faster-than-normal rate generally indicates inflammation in the body.
On the flip side, a normal ESR may be an indication that autoimmunity is not involved.
On the flip side, autoantibodies are proteins produced by the immune system that inappropriately attack healthy cells.
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.
High ferritin levels (hyperferritinemia) can be a sign of inflammatory diseases, infections, or cancer.
It may also be a sign of autoimmune disease.
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.
Theenzyme-linked immunosorbent assay (ELISA)sometimes referred to as the EIAis 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.
Of the three, IgAor specifically the lack of IgAmay indicate an autoimmune disease.
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.
In some cases, there may be no IgA detected at all.
Routine Blood Tests
Routine blood work is also a big part of diagnosing autoimmune diseases.
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.
There is no single blood test that can diagnose any autoimmune disease on its own.
MedlinePlus.C-reactive protein (CRP) test.
MedlinePlus.Erythrocyte sedimentation rate (ESR).
MedlinePlus.ANA (antinuclear antibody) test.
Lupus Research Alliance.ANA testing.
American College of Rheumatology.Antinuclear antibodies (ANA).
UCSF Health.Rheumatoid factor (RF).
MedlinePlus.Rheumatoid factor (RF) test.
University of California San Francisco.ELISA blood test.
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Immune Deficiency Foundation.Selective IgA deficiency.
UCSF Health.Fibrinogen blood test.
UCSF Health.Haptoglobin blood test.
UCSF Health.Albumin blood (serum) test.
