Rarely a patient with rheumatoid arthritis may develop the hyperviscosity syndrome.
Mechanism: intervascular formation of intermediate antibody complexes. These may consist of IgG and rheumatoid factor (IgM) or IgG and IgA.
Features of rheumatoid arthritis associated hyperviscosity syndrome:
(1) The patient develops signs and syptoms of the hyperviscocity syndrome.
(2) The patient has rheumatoid arthritis.
(3) Plasma hyperviscosity is increased to levels associated with symptoms.
(4) No other explanation for the hyperviscosity is identified.
(5) Therapy of the rheumatoid arthritis reduces the hyperviscosity.
Clinical findings may include:
(1) somnolence
(2) dilated retinal veins
(3) coagulopathy
(4) circulatory overload
Laboratory features may include:
(1) spurious hyponatremia
(2) negative anion gap
(3) hypergammaglobulinemia
(4) false negative tests for other autoantibodies
