Alternative vs. Once-Daily Oral Iron Supplementation in Iron Deficiency Anemia (IDA)

Inclusion criteria

• Male or female patients aged ≥20 years diagnosed with iron deficiency anemia, defined as: hemoglobin (Hb) <13 g/dL in males or <12 g/dL in females, and ferritin <50 ng/mL or transferrin saturation (TSAT) <20%.
• No iron supplementation within the past 3 months.

Exclusion criteria

• Hemodynamic instability (e.g., acute bleeding or hypotension).
• Severe heart failure (New York Heart Association [NYHA] Class III-IV) or other active cardiac diseases.
• Active malignancy or history of cancer within the past 3 years (except non-melanoma skin cancer).
• Pregnancy or breastfeeding.
• Chronic liver disease including cirrhosis (Child-Pugh class B or C).
• Chronic kidney disease (estimated glomerular filtration rate [eGFR] <60 mL/min/1.73 m²).
• Clinically significant thalassemia or hemoglobinopathies.
• Ongoing infection or chronic inflammatory diseases (e.g., rheumatoid arthritis, inflammatory bowel disease).
• Malabsorption disorders (e.g., history of bariatric surgery).
• Red blood cell transfusion within the past 3 months.

Withdrawal Criteria

• Withdrawal of informed consent.
• Severe adverse events requiring permanent discontinuation of study medication.
• Investigator's judgment that continued participation poses a safety risk.
• Non-adherence to study medication (compliance < 75%).

Treatment Failure

• Increase in hemoglobin level of < 1 g/dL at Week 4 or Week 8 compared with baseline.