Serum erythropoietin in myelomatosis

Erythropoietin activity in serum was measured using 59Fe incorporation into erythrocytes in protein-starved, hypoxic mice. The activity in serum from 20 patients with untreated myelomatosis was not significantly different from that in 31 saline controls. Only three patients had detectable erythropoietin levels in serum: 0.24 IU/ml, 0.27 IU/ml and 0.50 IU/ml (standard B), respectively. The venous haematocrit was correlated positively with the glomerular filtration rate as measured by 51Cr EDTA-clearance. No correlation could be established between venous haematocrit and serum albumin or serum transferrin. The results are in agreement with the assumption of a defective erythropoietin activity due to renal failure in myelomatosis.