Iron Deficiency

Iron deficiency is a state in which the body does not have enough available iron to meet physiological needs. It usually begins with depletion of iron stores and can progress to iron-restricted red-blood-cell production and, eventually, iron-deficiency anemia. Iron deficiency can therefore exist before the hemoglobin concentration becomes low enough to meet criteria for anemia .¹

Iron is required for hemoglobin and myoglobin as well as many enzymes involved in electron transport, metabolism, and cellular function. Deficiency can result from inadequate intake, impaired absorption, increased requirements, or blood loss. Which mechanism is most likely depends on age, sex, physiological state, diet, gastrointestinal function, and other clinical factors .¹

Laboratory assessment often includes ferritin and measures of circulating iron availability such as transferrin saturation, but no single marker is perfect in every setting. Ferritin reflects iron stores, yet it can rise during inflammation because it is also an acute-phase protein. Iron deficiency is therefore a biological state of inadequate iron availability, while iron-deficiency anemia is one later hematologic consequence of that state .¹