[Clinical significance of serum erythropoietin levels in patients with multiple myeloma].

Serum erythropoietin (Epo) levels were measured in 53 patients with multiple myeloma (MM), 49 normal subjects and 53 patients with some hematological diseases including aplastic anemia (AA), iron deficiency anemia, etc. to study the significance of erythropoietin in anemia of MM. The serum Epo level was 72.0 +/- 94.4 mIU/ml (mean +/- SD) in MM patients, which was significantly higher than in normal subjects (24.1 +/- 6.1 mIU/ml), but lower than in AA patients (7069.9 +/- 9406 mIU/ml). A significant inverse correlation was found between the hemoglobin (Hb) levels and the logarithmic values of serum Epo levels (r = -0.543, p < 0.05) in MM patients. This inverse correlation was stronger (r = -0.636, p < 0.05) in MM patients without renal dysfunction than in whole MM patients, while no correlation was observed in MM patients with renal dysfunction. These results indicate that MM patients with renal dysfunction have a low ability to synthesize Epo and that the supplemental therapy of recombinant Epo is effective to improve their anemia. In addition, the circadian rhythm of serum Epo level was lower in the morning than in the afternoon in both MM patients and normal controls. Serum Epo levels after chemotherapy in MM patients were elevated temporarily and then decreased in spite of no change of blood Hb level.