Erythropoietin/haemoglobin relationship in leukaemia and ulcerative colitis

The erythropoietin level was measured, by bioassay in polycythaemic mice, in the serum of anaemic patients suffering from different types of leukaemia. Comparative measurements were carried out in patients with ulcerative colitis. Serum erythropoietin was less well-correlated with the haemoglobin concentration in leukaemia than in ulcerative colitis. While serum erythropoietin did not exceed 200 mU/ml in patients with ulcerative colitis (lowest blood haemoglobin concentration 56 g/l), several of the leukaemic patients had serum erythropoietin levels above 500 mU/ml at comparable degrees of anaemia. Bone marrow biopsy showed that erythropoiesis was severely impaired in the leukaemic patients whose erythropoietin values were relatively high. These findings are in accord with the hypothesis that the plasma level of erythropoietin depends not only on the haemoglobin concentration of the blood but also on the bone marrow responsiveness to the hormone.