How to treat a patient with severe iron deficiency anemia and low hemoglobin, currently on vitamin C and iron (ferrous sulfate) 325, one tablet orally twice daily?

Treatment of Severe Iron Deficiency Anemia with Hemoglobin 7.9 g/dL

This patient requires immediate transition to intravenous iron therapy given the severe anemia (hemoglobin 7.9 g/dL) and current inadequate response to oral iron supplementation. 1

Rationale for Intravenous Iron

Your patient has severe iron deficiency anemia with hemoglobin well below 10 g/dL, which is a clear indication for IV iron therapy rather than continuing oral supplementation. 1 The current regimen of ferrous sulfate 325 mg twice daily (providing 130 mg elemental iron daily) 2 has failed to adequately correct the anemia, as evidenced by:

• Hemoglobin of 7.9 g/dL (severe anemia threshold is <10 g/dL) 1
• Iron saturation of 13.99% (below the 20% threshold indicating true iron deficiency) 1
• Low serum iron of 28 μg/dL with TIBC of 202 μg/dL 1

The 2024 AGA guidelines explicitly state that IV iron should be used when hemoglobin levels do not increase by 1 g/dL within 2 weeks of oral supplementation, or when ferritin does not improve within one month. 1 With a hemoglobin this low, the patient has clearly not responded adequately to oral therapy.

Specific Treatment Recommendations

Discontinue Current Oral Regimen and Initiate IV Iron

• Stop the twice-daily oral iron immediately – taking iron more than once daily increases side effects without improving absorption due to hepcidin elevation that persists 48 hours after each dose 1
• Administer IV iron formulations that can replace iron deficits in 1-2 infusions (such as ferric carboxymaltose or iron isomaltoside) rather than formulations requiring multiple visits 1
• IV iron delivers faster response rates and is safer than continuing ineffective oral therapy in severe anemia 1

Why IV Iron is Superior in This Case

The European consensus guidelines on anemia management state that IV iron is advisable for patients with severe anemia (hemoglobin <10 g/dL), those unresponsive to oral iron, and those with insufficient increase in serum iron parameters within the first 2 weeks of treatment. 1 Your patient meets all three criteria.

Oral iron absorption is inherently limited – more than 90% of ingested iron remains unabsorbed, leading to gastrointestinal side effects and potential oxidative stress from unabsorbed iron in the gut lumen. 1 Multiple randomized studies demonstrate that IV iron is at least as effective as oral iron with faster response rates. 1

Monitoring and Follow-Up

• Recheck hemoglobin within 2 weeks of IV iron administration – expect an increase of at least 1 g/dL 1
• Monitor ferritin and transferrin saturation to ensure adequate iron repletion (target ferritin 200-500 μg/L, transferrin saturation 30-40%) 1
• Investigate underlying cause of iron deficiency – severe IDA in any patient warrants evaluation for gastrointestinal blood loss, malabsorption, or other causes 1, 3

Regarding the Vitamin C Supplementation

The benefit of vitamin C with iron supplementation is minimal and clinically insignificant. 4, 5 A 2024 meta-analysis found that vitamin C supplementation was associated with only a 0.14 g/dL increase in hemoglobin (95% CI: 0.08-0.20), which is not clinically meaningful. 4 Another 2023 systematic review concluded that the evidence quality is very low and does not support routine vitamin C supplementation with iron therapy. 5

You may continue the vitamin C if already prescribed, but it will not meaningfully impact outcomes in this severely anemic patient. 1, 4

Common Pitfalls to Avoid

• Do not continue oral iron therapy hoping for delayed response – with hemoglobin this low, the patient needs rapid correction that only IV iron can provide 1
• Do not fear IV iron reactions – true anaphylaxis is extremely rare (approximately 1:200,000); most reactions are complement activation-related pseudo-allergy that can be managed by slowing the infusion rate 1
• Do not use intramuscular iron – there is no evidence it is more effective or less toxic than oral or IV iron 1

Consider Erythropoiesis-Stimulating Agents if Needed

If anemia does not improve despite IV iron therapy and control of any underlying inflammation, consider erythropoiesis-stimulating agents (ESAs) combined with continued IV iron supplementation. 1 However, this is typically reserved for refractory cases after adequate iron repletion has been achieved. Target hemoglobin with ESAs should be 11-13 g/dL to minimize thrombotic risk. 1

Blood Transfusion Consideration

Blood transfusion should be restricted to special clinical situations such as hemodynamic instability or severe anemia-related symptoms that are life-threatening. 1 While your patient has severe anemia at 7.9 g/dL, if they are hemodynamically stable and not experiencing acute symptoms requiring immediate correction, IV iron is the preferred initial approach to avoid transfusion-related risks including allosensitization. 1