4046, 4046-5 – RF IgM

Highlights

• Use of rabbit IgG as coating antigen and polyclonal anti-human IgM for detection
• Semi-quantitative detection of IgM RF
• Use as an aid in the diagnosis of rheumatoid arthritis (RA) in conjunction with clinical and laboratory findings
• Detection of IgM RF, the most frequent isotype associated with RA
• Use of high-specificity reagents, including rabbit IgG-coated microtiter strips and polyclonal anti-human IgM conjugate
• Manual test for professional in vitro diagnostic use
• CE marked

Intended Use

The RF IgM is a quantitative enzyme immunoassay for the determination of rheumatoid factor (RF) IgM in human serum. The assay specifically measures IgM antibodies directed against the Fc portion of IgG. RF IgM aids in the diagnosis of rheumatoid arthritis (RA) and helps clinicians assess disease activity and severity alongside clinical evaluation, imaging studies, and other laboratory tests. Laboratory professionals use the immunoassay manually to reliably and reproducibly quantify RF IgM levels, supporting effective patient management.

Diagnostic Relevance

Rheumatoid arthritis is the most common inflammatory joint disease. About 0.5 to 1.0 % of the population is affected worldwide. Painful joints in the fingers or toes are characteristic of rheumatoid arthritis, but knees, shoulders, hips or other joints may be also affected. The pain is often most pronounced in the morning. As the disease progresses, the number of affected joints usually increases. The diagnosis of rheumatoid arthritis is based on the clinical symptoms, imaging methods and laboratory analysis. In routine diagnostic services, the serological determination of rheumatoid factors is one of the classic and most frequently performed analyzes initially. Rheumatoid factors are mostly IgM antibodies directed against IgG antibodies and are detectable in the majority of patients with rheumatoid arthritis. They are therefore considered to be a sensitive marker for laboratory confirmation of rheumatoid arthritis.

High concentrations of RF often indicate a more severe form of the disease and lead to faster joint destruction. Clinicians also detect high RF levels in patients with extra-articular manifestations, including rheumatoid nodules, polyneuropathy, vasculitis, or Sicca syndrome. RF can belong to the IgG, IgM, or IgA isotype, and extra-articular symptoms appear more frequently in patients with IgA RF. Over time, clinicians consider IgA and IgG RF levels as prognostic markers for systemic disease progression. Like RF of the IgM isotype, high concentrations of IgG RF seems to appear with patients suffering from more progressive erosions of joints.