Anemia is a major public health problem that affects the population in rich and poor countries alike and is most prevalent in pregnant women and young children. The WHO estimates that worldwide 40% of pregnant women and 42% of children younger than 5 years old are anemic. Iron deficiency is the most common form of anemia.
Iron is an essential element and part of many metabolic pathways including transport and storage of oxygen. Iron uptake occurs through nutrition, mainly in its ferrous form (Fe2+). Oxidized to ferric iron (Fe3+) it is bound to the transport protein transferrin and delivered to target tissues. Excess iron is stored in a protein complex as ferritin, mainly present in liver, spleen and bone marrow.
Serum iron tests are typically ordered as follow up after abnormal results in routine blood tests. However, serum iron levels significantly vary throughout the day, as well as from day to day, depending on inter-individual variations and food intake among others.
Transferrin is the iron transport protein and approx. 30% saturated with iron in healthy individuals. The determination of the transferrin saturation is used in screening for hemochromatosis, for exclusion of iron overload in iron distribution disorders e.g. in liver diseases and in monitoring the erythropoietin treatment of patients with renal failure.
Alternatively, unsaturated iron binding capacity (UIBC) in combination with serum iron can be used to diagnose iron deficiency, chronic inflammatory disorders or malignancies. The sum of UIBC and serum iron gives a value for the total iron binding capacity (TIBC).
The first choice parameter for identification of iron deficiency is ferritin, the iron storage protein. Increased values can be found in iron overload, hemochromatosis chronic liver disease, inflammation and malignancy.
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