Rheumatic Disorders

Rheumatic disorders encompass dozens of different joint, muscle, and tendon conditions resulting from autoimmune reactions. These often lead to chronic inflammation causing pain and stiffness. Laboratory diagnostics play an important role in determining the severity and nature of the condition, complementing physical examination.

In vitro diagnostics

The following examples demonstrate how laboratory testing contributes to the detection, diagnosis, monitoring, and treatment of rheumatic disorders.

In vitro diagnostics

• Rheumatoid Arthritis

  Rheumatoid arthritis (RA) is a progressive disease affecting joints and muscles, caused by an unwanted immune response from the body - an autoimmune reaction. This produces autoantibodies leading to inflammation. The longer the disease remains undetected, the more damage occurs, ultimately becoming irreversible. While incurable, anti-inflammatory treatment can slow progression. Early diagnosis can prevent permanent damage.

  Anti-CCP test

  In rheumatoid arthritis (RA), the autoimmune response involves developing specific antibodies against citrullinated proteins. These are proteins where the amino acid arginine has been converted to citrulline. The immune system recognizes citrullinated proteins as foreign, resulting in antibody production - known as anti-citrullinated protein antibodies (ACPAs). These antibodies, highly specific for RA, are detectable in blood. They often appear very early in disease progression, sometimes long before symptoms develop, making them excellent biomarkers for early RA detection. The widely used anti-CCP test (anti-cyclic citrullinated peptide) is based on these ACPAs. Anti-CCP is measured in serum using ELISA. Combined with clinical presentation and RF testing, this anti-CCP test aids in RA diagnosis.

  Rheumatoid factor testing

  Rheumatoid factors are autoantibodies produced during autoimmune responses. The rheumatoid factor test (RF test) is a blood test that detects the presence of these factors. However, this test is not specific to rheumatoid arthritis (RA) as rheumatoid factors can also appear in other forms of rheumatism or infections. Furthermore, small amounts of rheumatoid factor can be found in healthy individuals. Therefore, clinical examination and additional tests are necessary for definitive diagnosis. The RF test helps differentiate rheumatic disorders from other conditions causing joint inflammation (arthritis) with similar symptoms (joint pain, inflammation, and stiffness).

  Anti-MCV test

  Another biomarker in the ACPA family is anti-mutated citrullinated vimentin (anti-MCV). This diagnostic marker is measured in serum using ELISA. While the anti-CCP test uses synthetic antigens (2-3 epitopes), the anti-MCV test employs natural human antigens (40 epitopes). This makes the anti-MCV ELISA highly sensitive and specific for early-stage RA detection. The sensitivity for early RA detection appears to increase further when both anti-CCP and anti-MCV are measured. The anti-MCV test is also valuable for disease severity prognosis and therapy monitoring.

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