Definitions and Relevance

Iron deficiency is defined as the decrease of the total content of iron in the body.

Iron deficiency anemia occurs when iron deficiency is sufficiently severe to reduce erythropoiesis. Iron deficiency anemia is a late manifestation of iron deficiency, but iron deficiency may be severe despite a normal hemoglobin. Functional iron deficiency occurs when iron stores are adequate but utilization is inadequate.

Bioavailable Iron

Absolute
Iron Deficiency

Iron Stores

Transport Iron

Reduced or absent iron stores in liver, spleen and bone marrow (24, 26)

Ferritin (iron stores) < 100 µg/L

Transferrin saturation (bioavailable iron) < 20%

Functional
Iron Deficiency

Iron Stores

Transport Iron

Bioavailable Iron

Adequate iron stores but inadequate utilization (29, 31)

= Restricted iron mobilization from stores, even if stores are normal. (28-30)

Ferritin (iron stores) 100-299 µg/L

Transferrin saturation (bioavailable iron) < 20%

Iron Deficiency Anemia

Iron deficiency can lead to anemia which when severe may require blood transfusions and be life-threatening. (13)

The risk associated with blood transfusions increases with the number of transfusions received. (13)

Severe iron deficiency anemia may lead to cardiovascular collapse and death. (14)

Decreased Health-Related Quality of Life

Iron deficiency (with and without anemia) has been shown to decrease health-related quality of life. (4-6)

Studies show improvement in energy levels, cardiovascular health, cognition, energy, and health-related quality of life with iron therapy. (4-6,10-11,17)

Iron deficiency and anemia can also exacerbate symptoms and worsen the prognosis of medical conditions, including heart failure and ischemic heart disease. Additionally, preoperative anemia is correlated with postoperative morbidity and mortality.

Neuro-Cognitive Development in Children (16-21)

Iron appears to be important for early neuro-cognitive development and iron deficiency anemia may be associated with developmental disadvantage in affected children.

Maternal anemia during pregnancy is associated with childhood autism spectrum disorder, intellectual disability and attention deficit hyperactivity disorder in early school years.

Maternal Anemia

Maternal anemia is associated with increased risk of maternal death, infection and hospitalization, and inhibited lactation. Adverse effects for the fetus include spontaneous abortion, premature delivery, and intrauterine fetal death, as well as increased risk of iron deficiency in children.

Iron deficiency is the most prevalent micro-nutrient deficiency in the world. (1)

The global prevalence of iron deficiency anemia is 33%. (2) In 2015, WHO deemed that 40% of cases of anemia were amenable to iron supplementation. (3) Iron deficiency is the only nutritional deficiency that is prevalent in low, middle and high income countries. (1) Iron deficiency may present with or without anemia. Non-anemic iron deficiency often goes unrecognized and is associated with symptoms that can negatively affect health related quality of life.

References

Definitions and Relevance

Absolute Iron Deficiency

Functional Iron Deficiency

Absolute
Iron Deficiency

Functional
Iron Deficiency