Abstract

Introduction: Early assessment of therapeutic response in iron deficiency anemia (IDA) remains challenging, as changes in total hemoglobin (Hb) concentration may require several weeks to become evident. Reticulocyte hemoglobin content (Ret Hb), also referred to as reticulocyte hemoglobin equivalent (RET-He), reflects real-time functional iron availability for erythropoiesis. Case Presentation: We report the case of a 24-year-old female with severe IDA (Hb: 10.7 g/dL, Ferritin: 3.1 ng/mL, Ret Hb: 21.6 pg) associated with Helicobacter pylori infection confirmed via stool antigen (Ag) test. Intervention: The patient was treated with two doses of intravenous ferric carboxymaltose (500 mg each) administered one week apart, followed by oral maintenance therapy with "Feblod" (iron, folic acid, B12, and vitamin C), one capsule daily for one month. Outcomes: A rapid increase in Ret Hb was observed within 72 hours of the first intravenous iron dose (rising from 21.6 pg to 28.0 pg, preceding normalization of MCV and Hb. Final serum ferritin reached 137.5 ng/mL by 17 November 2025. Conclusion: This case highlights Ret Hb as a dynamic, practical, and clinically valuable biomarker for early monitoring of bone marrow response to iron therapy. Take-home Message: A rise in Ret Hb within days confirms bone marrow response before significant changes in total Hb or MCV occur, optimizing clinical decision-making in complex IDA cases.

Key words: Iron deficiency anemia; Reticulocyte hemoglobin content; RET-He; Intravenous iron; Ferric carboxymaltose; Case report.