RHEUMATOID ARTHRITIS

What is Rheumatoid Arthritis?

In rheumatoid arthritis, the synovium of the joint becomes aggressive and inflamed. It enlarges and erodes (eats into) the neighboring bones, ligaments and joint cartilage coating damaging the joint's smooth surfaces. The end result is similar to osteoarthritis in that the joint surfaces are destroyed and painful, although rheumatoid arthritis starts differently and has additional problems both in the joint and elsewhere in the body.

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LABORATORY FINDINGS Synovial Fluid Yellow to white;  turbidity reflects increased WBC; fibrin clot indicates chronicity Mucin clot may be fair or poor;  a poor clot and decreased viscosity indicates that hyaluronic acid is decreasd. WBC - usually 5,000/ul - 50,000/ul - reflects the degree of inflammation Differential WBC - usually 65% neutrophils, which increase along with the total WBC Glucose - normal or low - there is interference with normal glucose transport *Positive rheumatoid factor - usually present in higher concentration than in serum; inversely related to the synovial-fluid complement level Decreased complement - reflects consumption in immunologic reaction Increased IgG and immune complexes Ragocytes - neutrophils with ingested immune complexes Peripheral Blood WBC are usually normal or slightly elevated (<12,000/ul).  WBC are decreased in the presence of splenomegaly;  this suggests Felty's syndrome. Normocytic or microcytic anaemia - chronic disease type Other Laboratory Findings *Positive rheumatoid factor (IgM) - 75% of patients; occurs in 95% of patients with subcutaneous nodules Presence of antinuclear antibodies (10%-50% of patients) - titres are lower than in SLE Negative anti-DNA antibodies Increased C-reactive protein, fibrinogen, and sedimentation rate - reflect disease activity Increased alpha1 and alpha2 - globulins - acute phase reactants Increased y-globulin - reflects accelerated protein breakdown in chronic disease Normal serum complement;  decreased complement in the presence of severe extra-articular disease, such as vasculitis Presence of circulating immune complexes - frequent when there are systemic manifestations *This finding is of diagnostic significance