What is the diagnosis and treatment for Iron-Resistant Iron Deficiency Anemia (IDA)?

From the Guidelines

Iron-resistant iron deficiency anemia (IRIDA) is a condition characterized by a lack of response to conventional oral iron supplementation, and in such cases, intravenous iron formulations should be considered as the primary treatment option.

Diagnosis and Treatment

The diagnosis of IRIDA is based on the presence of iron deficiency anemia that does not respond to oral iron supplementation, and the treatment should be tailored to the individual patient's needs.

• The initial treatment for IRIDA should include intravenous iron supplementation 1, with the choice of chemical form based on its registration for the specific age group or a proven good safety profile in adults.
• The total intravenous iron cumulative doses should be calculated based on formulas of the deficit of body iron, allowing for the correction of the hemoglobin (Hb) deficit and rebuilding the iron stores 1.
• Serum ferritin levels should be monitored and preferably should not exceed 500 mg/L to avoid toxicity of iron overload, especially in children and adolescents 1.
• The role of erythropoietin (EPO) treatment in IRIDA is controversial, and no recommendation can be made on its efficacy due to lack of evidence 1.

Monitoring and Follow-up

• Laboratory evaluation following IV iron should include a complete blood count (CBC) and iron parameters (ferritin, percent transferrin saturation (TSAT)) 4 to 8 weeks after the last infusion 1.
• Hemoglobin concentrations should increase within 1–2 weeks of treatment and should increase by 1 to 2 g/dL within 4–8 weeks of therapy 1.
• The frequency of lab monitoring is dependent on the cause of the ID, and those with recurrent blood loss will require more frequent and aggressive laboratory monitoring to diagnose and treat ID even in the absence of anemia 1.

From the FDA Drug Label

Injectafer is indicated for the treatment of: • iron deficiency anemia (IDA) in: adult and pediatric patients 1 year of age and older who have either intolerance or an unsatisfactory response to oral iron. adult patients who have non-dialysis dependent chronic kidney disease.

The diagnosis of Iron-Resistant Iron Deficiency Anemia (IDA) is not explicitly mentioned in the provided drug labels. However, based on the information provided, Iron Deficiency Anemia (IDA) can be diagnosed in patients who have either intolerance or an unsatisfactory response to oral iron. The treatment for IDA is ferric carboxymaltose (IV), which is administered intravenously. The recommended dosage varies based on the patient's weight and medical condition, as outlined in the drug label 2.

From the Research

Diagnosis of Iron-Resistant Iron Deficiency Anemia (IDA)

• Iron-deficiency anaemia (IDA) is usually suspected in at-risk patients with declining haemoglobin (Hb) levels and then confirmed by measuring serum ferritin levels and transferrin saturation 3
• Patients with inflammation should also be suspected of having iron-deficiency as anemia cause when transferrin saturation is low because serum ferritin can be spuriously normal 4

Treatment of Iron-Resistant IDA

• Oral iron preparations are commonly prescribed due to convenience and low cost, but their efficacy is limited by reduced absorption rate and gastrointestinal side-effects 3
• Intravenous (i.v.) iron is an alternative treatment option, which can bypass hepcidin actions by directly loading transferrin and making iron available to macrophages 3
• Second-generation i.v. iron formulations, including iron sucrose and ferric gluconate, are effective in managing IDA and have a lower risk of serious allergic reactions compared to i.v. iron dextran 3
• Newer i.v. iron preparations, such as ferric carboxymaltose and iron isomaltoside 1000, offer effective and rapid correction of IDA with a single dose of 1000 mg of iron 3, 5
• However, i.v. iron therapy is associated with a risk of severe infusion reactions and hypophosphatemia, particularly with ferric carboxymaltose 4, 6

Safety Considerations

• The safety profile of i.v. iron preparations is similar, with a low frequency of hypersensitivity reactions and cardiovascular events 5
• Hypophosphatemia is a common complication of i.v. iron therapy, particularly with ferric carboxymaltose, and can lead to severe fatigue, osteomalacia, and fractures 4, 6
• Individual selection of the appropriate iron therapy and evaluation of treatment response are mandatory to safely deliver improved outcomes through i.v. iron therapies 4