The goal of this clinical trial is to evaluate, if a change in dosing strategy in oral iron supplementation from leads to an improvement of iron absorption and consequently a faster therapy in patients with iron deficiency.

The main question the study aims to answer is: Does a treatment effect (measured by change in hemoglobin after 12 weeks of treatment) exist between daily oral iron supplementation and interval administration (every second day)? Participants will receive oral iron supplementation every second day with double the standard dose (intervention group). Researchers will compare this group with the active control group, that receives oral iron supplementation every day with the standard dose.

Participants will present for three patient visits (at baseline, after 6 and after 12 weeks of treatment).

Inclusion Criteria:

• Informed Consent signed by the subject
• ≥18 years of age
• Iron deficiency: Ferritin <30 µg/l
• hemoglobin ≥ 80 g/l
• CRP < 5 mg/l

Exclusion Criteria:

• Refusal of study participation,
• Regular administration of Erythropoietin
• Oral or intravenous iron supplementation <12 weeks prior to investigation
• Contraindications to intervention medication (Tardyferon), e.g. known hypersensitivity or allergy to iron sulfate / ferrous sulfate
• Blood transfusion or donation <12 weeks prior to investigation
• Active chemotherapy
• Inability to follow the procedures of the investigation, e.g. due to language problems, psychological disorders, dementia, etc. of the subject.

Note

Due to slow recruitment, the following inclusion criterion was removed on 09/25/2024 (MM/DD/YYYY):

Anemia (as defined by the WHO): Hemoglobin <130 g/L for men, Hemoglobin <120 g/l for women, Hemoglobin <110 g/l for pregnant women