Anemia associated with uremia has not suffered for want of plausible, well-documented explanations. Suggested mechanisms have included hemolysis, blood loss, decreased absorption and utilization of iron, and deficiency of erythropoietin. The question is not so much whether these factors are operative, but what is their order of priority. Does any one of these mechanisms bear a major responsibility for the anemia?
An answer emerges from a number of recent studies. Reporting his own researches and reviewing the literature, Erslev1 relates the etiology of the anemia in chronic renal failure to one or more of three factors: the nature of primary disease, the retention of toxins, and decrease in erythropoietin activity.
If the primary disease is pyelonephritis or disseminated lupus erythematosus, the anemia may be due to a block in the release of iron from reticulo-endothelial iron stores. In multiple myeloma plasma cells may replace the marrow's red cell mass.