At what age should iron deficiency screening be performed in infants?

Iron Deficiency Screening in Infants

Screen all infants for iron deficiency anemia at 9-12 months of age, with a repeat screening 6 months later (at 15-18 months). 1

Universal vs. Selective Screening Approach

The screening strategy depends on population risk:

High-Risk Populations (Universal Screening)

• Screen ALL children at 9-12 months, again 6 months later, and annually from ages 2-5 years if they belong to high-risk groups including: 1
  • Children from low-income families 1
  • Children eligible for WIC 1
  • Migrant or recently arrived refugee children 1

Low-Risk Populations (Selective Screening)

• Screen only children with specific risk factors at 9-12 months and again at 15-18 months 1

Risk Factors Requiring Screening at 9-12 Months

Screen infants who have ANY of the following risk factors:

• Preterm or low-birthweight infants (consider screening even before 6 months if not receiving iron-fortified formula) 1
• Infants fed non-iron-fortified formula for >2 months 1
• Infants introduced to cow's milk before 12 months 1
• Breastfed infants without adequate iron intake after 6 months (insufficient iron from supplementary foods) 1
• Children consuming >24 oz of cow's milk daily 1
• Children with special health-care needs (medications interfering with iron absorption, chronic infection, inflammatory disorders, restricted diets, or extensive blood loss) 1

Optimal Screening Timing: The Evidence

While CDC guidelines recommend 9-12 months 1, emerging research suggests 15-18 months may be more optimal for detecting iron deficiency 2. The rationale:

• Serum ferritin levels decline most rapidly between 12-15 months (9% decrease per month), then stabilize from 15-24 months 2
• Screening at 9-12 months may be too early to detect anemia in infants receiving iron-fortified formulas, as insufficient time has elapsed for iron deficiency anemia to develop 3
• Screening at 15-18 months allows adequate time for nutritional anemia to manifest after weaning from iron-fortified formula and accounts for toddler dietary patterns 3

Screening Method

• Use hemoglobin or hematocrit as the initial screening test 1
• Hemoglobin <110 g/L indicates anemia requiring further evaluation 2
• Consider serum ferritin (≤15 μg/L confirms iron deficiency) for more accurate detection, as hemoglobin alone has poor sensitivity (25%) for iron deficiency 4, 2
• Concurrent CRP measurement is generally unnecessary in low-risk children (only 3.3% have elevated CRP ≥10 mg/L) 2

Common Pitfalls to Avoid

• Do not rely solely on hemoglobin screening - it only detects iron deficiency severe enough to cause anemia, missing earlier stages of deficiency 5
• Do not screen too early (before 9 months) in well-nourished infants receiving iron-fortified formula, as anemia may not yet be evident 3
• Do not forget the 6-month follow-up screening at 15-18 months, which is critical for detecting iron deficiency that develops during the toddler period 1