When should I replete iron stores in a patient with anemia and a ferritin level of 45?

From the Guidelines

Iron repletion is recommended for your patient with anemia and a ferritin level of 45 ng/mL, as this level suggests iron deficiency contributing to the anemia. According to the American Gastroenterological Association (AGA) guideline, a ferritin cut-off value of 45 mg/dL is recommended for diagnosing iron deficiency in individuals with anemia, as it has an optimal balance of sensitivity and specificity 1.

Key Considerations for Iron Repletion

• Begin with oral iron supplementation, such as ferrous sulfate 325 mg (containing 65 mg elemental iron) taken once or twice daily on an empty stomach with vitamin C to enhance absorption.
• Alternatively, consider ferrous gluconate 300 mg or ferrous fumarate 200 mg if sulfate causes intolerable gastrointestinal side effects.
• Continue supplementation for 3-6 months to fully replenish iron stores, even after hemoglobin normalizes.
• For patients with malabsorption, intolerance to oral therapy, or severe anemia, intravenous iron formulations like iron sucrose or ferric carboxymaltose may be necessary, as indicated by the AGA clinical practice update on management of iron deficiency anemia 1.

Rationale for Treatment

A ferritin level below 50 ng/mL in the presence of anemia strongly suggests iron deficiency, as ferritin is the primary storage protein for iron in the body. While ferritin is an acute phase reactant that can be elevated in inflammatory conditions, a level of 45 ng/mL is low enough to warrant treatment in an anemic patient, particularly if other iron studies like transferrin saturation are also low. The goal of iron repletion is to improve quality of life and decrease the risk of complications related to anemia, as stated in the AGA clinical practice update 1.

Monitoring and Adjustments

It is essential to monitor the patient's response to iron supplementation, with expectations of increased hemoglobin levels and improved iron stores. If the patient cannot tolerate oral iron or does not respond to oral iron supplementation, intravenous iron may be necessary, as guided by the AGA recommendations 1.

From the Research

Iron Repletion in Anemia with Ferritin 45

• The decision to replete iron stores in a patient with anemia and a ferritin level of 45 should be based on the underlying cause of the anemia and the patient's overall clinical condition 2.
• According to the study, iron deficiency is diagnosed by low serum ferritin (typically <30 ng/mL) in individuals without inflammatory conditions or by transferrin saturation (iron/total iron binding capacity × 100) less than 20% 2.
• Since the patient's ferritin level is 45, which is above the typical threshold for iron deficiency, it is essential to investigate the underlying cause of the anemia and assess for any symptoms or conditions that may indicate a need for iron repletion 2.
• The study suggests that oral iron (ferrous sulfate 325 mg/d or on alternate days) is typically first-line therapy for iron deficiency anemia, while intravenous iron is indicated for patients with oral iron intolerance, poor absorption, or certain chronic inflammatory conditions 2.
• Other studies have shown that iron deficiency anemia can be related to Helicobacter pylori infection, and eradication of this infection can lead to the disappearance of anemia and ferropenia 3.
• In cases of chronic disorders such as chronic kidney disease, chronic heart failure, and chronic inflammatory disorders, the diagnosis and treatment of iron deficiency anemia may also incorporate transferrin saturation and intravenous iron therapy 4.
• The amount of blood loss can be determined using the storage iron decrease rate (SID) as obtained from serum ferritin after intravenous iron therapy, which can help guide iron repletion therapy 5, 6.