Oral iron replacement may not be effective in cases of iron deficiency due to malabsorption, such as celiac disease, inflammatory bowel disease, or H. pylori infection; these cases would require treatment of the underlying disease to increase oral absorption or intravenous iron replacement.As iron-deficiency anemia becomes more severe, if the anemia does not respond to oral treatments, or if the treated person does not tolerate oral iron supplementation, then other measures may become necessary. Two options are intravenous iron injections and blood transfusion. Intravenous can be for people who do not tolerate oral iron, who are unlikely to respond to oral iron, or who require iron on a long-term basis. For example, people receiving dialysis treatment who are also getting erythropoietin or another erythropoiesis-stimulating agent are given parenteral iron, which helps the body respond to the erythropoietin agents to produce red blood cells.Intravenous iron can induce an allergic response that can be as serious as anaphylaxis, although different formulations have decreased the likelihood of this adverse effect. In certain cases intravenous iron is both safer and more effective than the oral route. For patients with severe anemia such as from blood loss, or who have severe symptoms such as cardiovascular instability, a blood transfusion may be considered.Ferric derisomaltose (Monoferric) was approved in the United States in January 2020, for the treatment of iron deficiency anemia. Epidemiology
A moderate degree of iron-deficiency anemia affects approximately 610 million people worldwide or 8.8% of the population. It is slightly more common in females (9.9%) than males (7.8%).
The Population Reference Intakes are higher than the US Recommended Dietary Allowances, with the exception of pregnancy. Iron malabsorption
Iron from food is absorbed into the bloodstream in the small intestine, primarily in the duodenum. Iron malabsorption is a less common cause of iron-deficiency anemia, but many gastrointestinal disorders can reduce the bodys ability to absorb iron. There are different mechanisms that may be present. In celiac disease, abnormal changes in the structure of the duodenum can decrease iron absorption. Abnormalities or surgical removal of the stomach can also lead to malabsorption by altering the acidic environment needed for iron to be converted into its absorbable form. If there is insufficient production of hydrochloric acid in the stomach, hypochlorhydria/achlorhydria can occur (often due to chronic H. pylori infections or long-term proton-pump inhibitor therapy), inhibiting the conversion of ferric iron to the absorbable ferrous iron.Bariatric surgery is associated with an increased risk of iron deficiency anemia due to malabsorption of iron. During a Roux-en-Y anastamosis, which is commonly performed for weight management and diabetes control, the stomach is made into a small pouch and this is connected directly to the small intestines further downstream (bypassing the duodenum as a site of digestion). About 17-45% of people develop iron deficiency after a Roux-en-Y gastric bypass. Pregnant women
Without iron supplementation, iron-deficiency anemia occurs in many pregnant women because their iron stores need to serve their own increased blood volume, as well as be a source of hemoglobin for the growing baby and for placental development.