Hemoglobin Response to a Low-Iron Dose in Infantile Anemia

Iron-deficiency anemia (IDA) is common during infancy, especially among infants exclusively breastfed after six months of age. The recommended therapeutic iron dose is 3-6 mg/kg/day; however, excessive iron load can be harmful due to alteration of the gut microbiome and oxidative stress to the developing organs. Lower doses of iron have shown efficacy in treating IDA in adults. This retrospective study evaluated the hemoglobin (Hb) response to a lower iron dose in infantile anemia.

During health checkups for 9- to 10-month-old infants, anemia screening was conducted for those who were exclusively breastfed. Clinical parameters, including birth date, gestational age, birth weight, and body weight at the start of iron supplementation, were recorded. Venous blood samples were collected for a complete blood count (CBC). Infants with either Hb levels below 11.0 g/dL or mean corpuscular volume below 70 fL received a therapeutic iron trial. From March 2016 to November 2018, a fixed dose of elemental iron (soluble ferric pyrophosphate) 15 mg/day was administered (reference group), and from November 2018 to December 2023, a dose of 1 mg/kg/day was given (low-dose group). CBC measurements were repeated after four weeks, and Hb responses were compared between the two regimens.

A total of 26 children in the reference group and 27 in the low-dose group were finally analyzed. The fixed 15 mg/day dose in the reference group corresponded to 1.8 (1.6-1.9) (median (interquartile range) mg/kg/day). Baseline clinical variables showed no statistically significant differences between the two groups. The median Hb increase was 1.6 g/dL and 1.5 g/dL, with 69% (18/26) and 70% (19/27) of children achieving an Hb level ≥ 1 g/dL, in the reference and low-dose groups, respectively. All 15 children (15/27, 56%) in the low-dose group, who met the new WHO anemia definition at the age of 6-23 months of Hb < 10.5 g/dL, had an Hb response ≥ 1.0 g/dL, with a median Hb response of 2.2 g/dL.

An iron dose of 1 mg/kg/day was as effective as 15 mg/day (median: 1.8 mg/kg/day) in the Hb response. In all children with Hb < 10.5 g/dL, the iron dose of 1 mg/kg/day showed substantial Hb responses. These findings suggest that therapeutic iron doses lower than conventional recommendations may be effective for managing IDA and mitigating the harmful effects.