What dose of Enfamil Poly‑Vi‑Sol (iron supplement) should be given to a healthy, full‑term, exclusively breast‑fed 5‑month‑old infant weighing approximately 6–7 kg?

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Dosing Poly-Vi-Sol with Iron for a 5-Month-Old Breastfed Infant

For a healthy, full-term, exclusively breastfed 5-month-old infant weighing 6–7 kg, give 1 mg/kg/day of elemental iron, which translates to approximately 6–7 mg of elemental iron daily (roughly 0.6–0.7 mL of Poly-Vi-Sol with Iron, depending on the formulation). 1, 2, 3

Timing and Rationale

  • American guidelines recommend starting iron supplementation at 4 months of age for exclusively breastfed term infants at a dose of 1 mg/kg/day. 1, 2, 3

  • This recommendation reflects that term infants are born with adequate iron stores lasting approximately 4–6 months, after which external iron becomes necessary. 4, 2

  • At 5 months, your patient is already past the recommended initiation point and should begin supplementation immediately. 1, 3

Practical Dosing Calculation

  • For a 6 kg infant: 6 kg × 1 mg/kg/day = 6 mg elemental iron daily 1, 3

  • For a 7 kg infant: 7 kg × 1 mg/kg/day = 7 mg elemental iron daily 1, 3

  • Most Poly-Vi-Sol with Iron formulations contain approximately 10 mg elemental iron per 1 mL, so you would administer 0.6–0.7 mL daily. Verify the exact concentration on your specific product label. 1, 3

Duration and Continuation

  • Continue iron supplementation throughout the exclusive breastfeeding period and until the infant is consuming adequate iron-rich complementary foods (typically introduced around 6 months). 1, 2

  • Once complementary foods begin at 6 months, prioritize iron-fortified infant cereal (≥2 servings daily), pureed meats, and vitamin C-rich foods to enhance absorption. 2, 3

Evidence Strength and Nuances

  • The American Academy of Pediatrics classifies this as a moderate-strength recommendation, noting that routine supplementation before 4 months offers no additional benefit in low-prevalence anemia populations. 1

  • Research shows that 15–25% of breastfed infants develop iron deficiency by 9–12 months without adequate dietary iron, supporting early supplementation. 4, 2

  • Studies demonstrate that while breast milk has the highest bioavailability of iron (~50% vs. ~10% in formula), it contains only 0.35 mg/L, which is insufficient after 4–6 months. 3, 5

Common Pitfalls to Avoid

  • Do not delay supplementation beyond 6 months in exclusively breastfed infants, as iron deficiency anemia typically manifests around 9 months but iron stores are depleted earlier. 4, 2

  • Avoid giving cow's milk, goat's milk, or soy milk before 12 months, as these contain minimal bioavailable iron and may cause occult gastrointestinal bleeding. 4, 2

  • Do not assume maternal iron supplementation will improve infant iron status—breast milk iron content remains low regardless of maternal intake. 2, 3

Monitoring Considerations

  • For this healthy term infant, routine screening is not necessary unless risk factors emerge (low socioeconomic status, inadequate complementary foods after 6 months). 2

  • High-risk infants should be screened at 9–12 months with hemoglobin and ferritin testing. 2

  • If iron deficiency anemia is diagnosed, increase the dose to 3 mg/kg/day and continue for 2 months after hemoglobin normalizes (approximately 3 months total). 3

References

Guideline

Supplementation Guidelines for Breastfed Infants

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2026

Guideline

Iron Supplementation Guidelines for Infants

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2026

Guideline

Iron Supplementation Guidelines for Infants

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2026

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Iron requirements of infants and toddlers.

Journal of pediatric gastroenterology and nutrition, 2014

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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