Updates in the Management of Iron Deficiency Anemia

Lilian White, MD
Posted on April 28, 2025

Iron deficiency is the most common cause of anemia globally, comprising an estimated 50% of patients with anemia. Women younger than 50 years are the most likely population to be affected. Iron deficiency due to poor nutrition is the most common cause of anemia in children. Iron deficiency without anemia is estimated to be twice as prevalent as iron deficiency with anemia. Iron deficiency anemia is caused by gastrointestinal bleeding, menstrual blood loss, impaired absorption (e.g., celiac disease), inadequate dietary intake, and inflammatory conditions (e.g., chronic kidney disease).

Iron deficiency results from reduced iron intake, absorption, losses or reduced mobilization of iron from bodily stores. Effects of iron deficiency anemia include reduced cognition in children and older adults, as well as adverse pregnancy outcomes.

The diagnosis of iron deficiency anemia is generally based on deficient iron stores and anemia. A serum ferritin level of < 45 mg/dL is indicative of iron deficiency, demonstrating an 85% sensitivity and 92% specificity for diagnosing iron deficiency in patients with anemia.

This threshold is recommended by the American Gastroenterological Association (AGA). In patients with an elevated serum ferritin due to inflammation, alternative markers of iron status such as transferrin saturation may be considered.

In adults, evaluation of iron deficiency anemia involves noninvasive screening for celiac disease and Helicobacter pylori infection. The AGA guidelines additionally recommend bidirectional endoscopy in men and postmenopausal women with iron deficiency anemia. Endoscopy may also be considered in premenopausal women; however, a trial of oral iron supplementation is a reasonable initial step in these patients in the absence of concerning symptoms. A hemoglobin increase of greater than 1.0 g/dL over 1 month is considered a successful response and supports the diagnosis.

In children, mild iron deficiency anemia may be treated initially with oral iron supplementation for 1 month without additional testing. As in adults, an increase of greater than 1.0 g/dL of hemoglobin over 1 month is considered supportive of the diagnosis. In those who do not respond to empiric treatment, further evaluation for gastrointestinal bleeding and referral to a gastroenterologist is recommended.

According to a recent AGA Clinical Practice Update, ferrous sulfate is the preferred form of iron replacement due to its affordability. However, the guidelines indicate that no specific form of iron supplementation has demonstrated superior effectiveness. Several studies have demonstrated the improved tolerability of iron bisglycinate compared with ferrous sulfate, noting fewer gastrointestinal adverse effects and similar effectiveness in adults and children. The cost of iron bisglycinate supplementation is about $15 for 60 tablets vs $10 for 200 tablets of iron sulfate, making it a little more expensive. Additionally, availability in pharmacies may vary.

Intravenous (IV) iron replacement is typically recommended by the AGA updated guidelines for patients who cannot tolerate oral iron, exhibit poor absorption (e.g., in patients with irritable bowel disease, a history of gastric bypass surgery), or fail to demonstrate improvement with oral iron supplementation. Compared with oral iron, IV iron does not reduce mortality or the need for blood transfusions in adults with iron deficiency anemia, and it may increase the risk of infection, according to a 2022 FPIN Clinical Inquiry.