When should iron supplementation be started in a child with avoidant/restrictive food intake disorder (ARFID) who has iron deficiency but a normal hemoglobin level?

Iron Supplementation in ARFID Children with Low Iron

Start iron supplementation immediately when iron deficiency is confirmed by laboratory testing, even if hemoglobin is normal, because iron deficiency without anemia still depletes iron stores and can impair neurodevelopment in children. 1, 2

When to Supplement: The Decision Algorithm

Immediate Supplementation Criteria

• Begin treatment as soon as serum ferritin ≤15 μg/L is documented, regardless of hemoglobin level 1, 3
• Low serum ferritin is the most specific indicator of depleted iron stores and warrants immediate intervention 4
• In ARFID children, where dietary intake is severely restricted, do not wait for anemia to develop before starting supplementation 2, 5

Dosing Protocol

• Administer 3 mg/kg/day of elemental iron in liquid/drop formulation 1, 3
• Give between meals to maximize absorption, though this may increase gastrointestinal side effects 1
• Ferrous sulfate is the preferred formulation due to cost-effectiveness and known elemental iron content 3

Why Normal Hemoglobin Doesn't Mean "Wait and See"

Iron deficiency progresses through stages: first iron stores deplete (low ferritin), then iron-deficient erythropoiesis occurs, and finally anemia develops 4. In children, especially those with ARFID, waiting until anemia appears means missing the critical window to prevent neurodevelopmental consequences 5. Severe and prolonged iron deficiency in early childhood causes cognitive deficits that may not be fully reversible even after correction 5.

The ARFID Context Makes This More Urgent

• ARFID children have chronically inadequate dietary iron intake due to food avoidance patterns 5
• Unlike typical picky eaters, ARFID represents a persistent feeding disorder where spontaneous dietary improvement is unlikely without intervention 5
• These children are at continuous risk for progression from iron depletion to iron deficiency anemia 2, 5

Monitoring and Duration

Initial Response Check

• Recheck hemoglobin after 4 weeks of treatment 1, 3
• An increase of ≥1 g/dL hemoglobin or ≥3% hematocrit confirms iron deficiency as the underlying problem 1, 3
• If no response occurs despite documented compliance and absence of acute illness, obtain MCV, RDW, and repeat ferritin to evaluate for alternative causes 1, 3

Treatment Duration

• Continue iron for 2 months after hemoglobin normalizes, totaling approximately 3 months of treatment 1, 3
• This extended duration is necessary to replenish iron stores, not just correct hemoglobin 1, 3
• Recheck hemoglobin at the end of the 3-month course and reassess approximately 6 months later to monitor for recurrence 3

Adjunctive Dietary Strategies for ARFID

While supplementation is the primary intervention, work simultaneously on dietary modifications within the child's tolerance:

• Pair any tolerated iron-containing foods with vitamin C-rich options to enhance absorption 1, 2
• Limit cow's milk to <24 oz/day if the child consumes milk, as excessive intake displaces iron-rich foods and can cause occult blood loss 3
• Consider iron-fortified cereals if texture/taste are acceptable to the child 2

Common Pitfalls in ARFID Patients

Don't Make These Mistakes

• Do not delay supplementation hoping dietary counseling alone will resolve the deficiency – ARFID is a psychiatric feeding disorder requiring behavioral intervention that takes months to years 5
• Do not use "watchful waiting" with serial ferritin checks – each month of iron deficiency in a young child risks neurodevelopmental impact 5
• Do not assume normal hemoglobin means adequate iron status – ferritin is the earlier and more specific marker 4, 1
• Do not stop treatment when hemoglobin normalizes – continue for 2 additional months to replenish stores 1, 3

Special Consideration for Non-Response

If the child fails to respond to oral iron after 4 weeks of documented compliance, consider 6, 7:

• Malabsorption (though less common in isolated ARFID)
• Ongoing occult blood loss
• Incorrect diagnosis (check MCV, RDW, ferritin >15 μg/L suggests alternative etiology) 1, 3
• In refractory cases, newer oral formulations (liposomal iron, iron glycinate) have fewer gastrointestinal side effects and may improve adherence 7
• Intravenous iron is reserved for true oral intolerance or malabsorption 6, 7