Absolute vs Functional Iron Deficiency
The etiology of anemia is variable and may be the result of an absolute or a functional iron deficiency1,2,3
Absolute Iron Deficiency
Responsive image
Functional Iron Deficiency
Responsive image
Absolute iron deficiency occurs when total body iron stores become depleted, commonly due to poor dietary intake or occult bleeding. The amount of stored iron is no longer adequate to meet the demands for erythropoiesis.1,4
Functional iron deficiency refers to the failure to release iron rapidly enough to keep pace with the demands of the bone marrow for erythropoiesis. Functional iron deficiency may occur even when the body has adequate iron stores. As a result, TSAT is often low in these patients despite a normal or elevated ferritin.2 This condition can be caused by:
  • The use of erythropoietin-stimulating agents (ESAs) that rapidly deplete circulating iron2
  • Inflammation (eg, inflammatory bowel disease or rheumatoid arthritis) may cause release of hepcidin, decreasing the availability of transferrin-bound iron in the blood.1,2
The spectrum of iron deficiency5
Responsive image