Iron deficiency – consequences and evaluation markers

Iron is an essential trace element, located within each cell, the bulk of which is found in the erythrocytes. It is absorbed mainly in the duodenum. If the organism does not need iron, it is stored in the form of ferritin. The concentration of plasma and serum ferritin is proportional to the size of body iron stores in healthy individuals and those with early iron deficiency. When the serum ferritin concentration falls below 12 μg/L, the iron stores are totally depleted. An increased total iron-binding capacity (> 400 μg/dL) is therefore indicative of storage iron depletion. It is less precise than the serum ferritin concentration. During iron deficiency the participation of iron in heme formation is reduced, which leads to a gradual accumulation of protoporphyrin. The serum transferrin receptor (sTfR) is a more sensitive indicator of iron deficiency. The elevated sTfR is the first laboratory criterion of iron deficiency after the depletion of the iron stores in the organism and its increase continues in direct proportion to the severity of the iron deficiency. Each evaluation of the iron status should include the Hb concentration, since it is indicative of a more advanced stage of iron deficiency.