Microcytic anaemia in juvenile chronic arthritis.

The degrees of anaemia and microcytosis in 100 patients with juvenile chronic arthritis (JCA) were analysed according to the pattern of disease and its activity. Microcytosis was common (40% of patients had a mean corpuscular volume (MCV) of less than 75 fl), sometimes severe (MCV less than 65 fl in 14 patients), and closely correlated with the severity of the anaemia. The degrees of microcytosis and anaemia were both directly related to disease activity as measured by the ESR, and were most severe in cases with the systemic form of JCA. In 50 patients iron status was assessed. The serum iron concentration was directly related to the MCV, whereas the serum ferritin was inversely related to MCV and haemoglobin concentration and directly related to the ESR. Bone marrow iron stores were normal or increased in 6 patients with severe microcytic anaemia. These data suggest that the anaemia of JCA is typically microcytic, and that this microcytosis is associated with the disturbance of iron metabolism seen in the 'anaemia of chronic disorders' rather than overall depletion of body iron.