The Anaemia of Rheumatoid Arthritis: The Significance of Iron Deposits in the Synovial Membrane

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Abstract
Summary: Histological examination of synovial membrane removed from 100 joints in 81 patients with rheumatoid arthritis has shown iron deposits, often of an extensive nature in 96 joints. Electron microscopic examination revealed ferritin within synovial cell cytoplasm and concentrated into lysosomes in 16 of 20 biopsies. It is suggested that the iron deposits arise from continued oozing of blood from the vascular granulation tissue into the synovial cavity. The sequence from erythrophagocytosis to ferritin formation can be followed with the electron microscope. It is also likely that some of the iron given as parenteral therapy finds its way into synovial macrophages.In 28 patients a highly significant relationship was found between the presence of anaemia due to rheumatoid arthritis and the histological estimate of the extent of iron deposits. There was also a relationship between the duration of disease in the joint, the grade of x‐ray change and the iron deposits.The synovial membrane appears to be an important source of iron sequestration. A delay in release of iron from this and the reticuloendothelial storage sites could explain many of the features of the anaemia of rheumatoid arthritis.