What is the best treatment for a patient with iron deficiency anemia and lab values of ferritin 262, iron 18, transferrin 120, TIBC 172, transferrin saturation 10%, and hemoglobin 9.6?

Functional Iron Deficiency with Inflammation: Intravenous Iron Indicated

This patient has functional iron deficiency (FID) despite elevated ferritin, characterized by transferrin saturation of 10% with ferritin 262 ng/mL, and should receive intravenous iron supplementation rather than oral iron. 1

Understanding the Iron Profile

This laboratory pattern represents functional iron deficiency in the setting of inflammation, not true iron sufficiency:

• Transferrin saturation of 10% is severely low (normal >20%), indicating inadequate iron delivery to erythroid precursors for hemoglobin synthesis 1
• Ferritin 262 ng/mL is elevated as an acute phase reactant, masking underlying iron deficiency 1
• Low serum iron (18) with low TIBC (172) confirms iron-restricted erythropoiesis 1
• Hemoglobin 9.6 g/dL represents significant anemia requiring treatment 1

The elevated ferritin does not indicate adequate iron stores in this context—it reflects inflammation causing iron sequestration in reticuloendothelial cells while functional iron for erythropoiesis remains depleted 1.

Treatment Recommendation: Intravenous Iron

Why IV Iron Over Oral Iron

Intravenous iron is strongly preferred for this patient because:

• Transferrin saturation <20% with ferritin 100-700 ng/mL indicates functional iron deficiency where oral iron absorption is impaired by hepcidin upregulation 1
• Studies demonstrate only 21% of patients with this profile respond to oral iron after initial failure, compared to 65% responding to IV iron 1
• Inflammation-induced hepcidin blocks intestinal iron absorption, making oral supplementation ineffective 1

Specific IV Iron Protocol

Administer IV iron as a therapeutic trial:

• Ferric carboxymaltose or iron sucrose 50-125 mg weekly for 8-10 doses 1
• Monitor hemoglobin response after 6-8 weeks (not earlier, as ferritin remains falsely elevated immediately post-infusion) 1
• If hemoglobin increases by ≥1 g/dL, this confirms functional iron deficiency and justifies continued therapy 1
• If no response occurs, suspect inflammatory block and discontinue iron until inflammation resolves 1

Safety Considerations with Elevated Ferritin

The DRIVE study specifically addressed safety of IV iron in patients with ferritin 500-1200 ng/mL and transferrin saturation <25%:

• IV iron increased hemoglobin significantly more than controls (16±13 vs 11±14 g/L, P=0.028) 1
• Baseline ferritin level did not predict iron responsiveness—transferrin saturation was the key determinant 1, 2
• No significant increase in serious adverse events, though long-term safety data remain limited 1

At ferritin 262 ng/mL, this patient is well below the 500 ng/mL threshold studied, making IV iron both safer and more clearly indicated 1.

Oral Iron: Not Recommended as First-Line

Oral iron (ferrous sulfate 324 mg containing 65 mg elemental iron daily) 3 would be:

• Poorly absorbed due to inflammation-induced hepcidin elevation 1
• Slower to correct anemia, requiring 8-10 weeks minimum 1
• Associated with gastrointestinal side effects causing poor compliance 1

Consider oral iron only if IV access is problematic or after inflammation resolves 1.

Monitoring Strategy

Reassess in 6-8 weeks (not sooner):

• Hemoglobin, transferrin saturation, ferritin 1
• Target transferrin saturation >20% for adequate iron delivery 1
• Continue IV iron until hemoglobin normalizes and transferrin saturation stabilizes >20% 1

Critical Pitfall to Avoid

Do not withhold iron based solely on ferritin >100 ng/mL when transferrin saturation is severely low (<20%) 1. This represents the most common error in managing functional iron deficiency—the ferritin reflects inflammation, not iron sufficiency 1. The transferrin saturation of 10% is the dominant finding requiring treatment 1.