Plasma erythropoietin assay in patients with chronic renal failure

Using the post-hypoxic mouse method of assay, values for erythropoietin in the plasma of patients with chronic renal failure were equal to, or greater than, normal values. Results suggest that the source of erythropoietin may be primarily extrarenal. Normal renal tissue, provided in the assay by the intact mouse, is required for activation of the hormone. There still remains to be explained the enhanced erythropoietic response to haemorrhage or hypoxia that can occur in anephric man.