4027-5 – RF IgA

Intended Purpose

The RF IgA is a quantitative immunoassay for the determination of rheumatoid factor (RF) IgA in human serum. The RF IgA is intended as an aid in the diagnosis of rheumatoid arthritis (RA) in conjunction with other clinical and laboratory findings. The immunoassay is designed for manual professional in vitro diagnostic use.

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 are often associated with a more severe disease comprising a faster destruction of joints. In addition, they are found in patients with extra-articular manifestations such as rheumatoid nodules, polyneuropathy, vasculitis or Sicca syndrome. RF may belong to the IgG, IgM or IgA isotype where extra-articular manifestations seem to be associated with IgA RF. In long- time, RA IgA and IgG RF are considered to be prognostic markers for systemic manifestation. Like RF of the IgM isotype, high concentrations of IgG RF seems to appear with patients suffering from more progressive erosions of joints.