What is the recommended pediatric dosing of ferrous fumarate for treatment and prophylaxis of iron‑deficiency anemia, including dose per kilogram and administration schedule?

Pediatric Ferrous Fumarate Dosing

For treatment of iron-deficiency anemia in pediatric patients, administer 3 mg/kg/day of elemental iron (approximately 9 mg/kg/day of ferrous fumarate salt) given between meals, divided into 1-2 doses daily for optimal absorption and tolerability. 1, 2

Elemental Iron Content

• Ferrous fumarate contains approximately 33% elemental iron by weight (108 mg elemental iron per 325 mg tablet, or 69-106 mg per standard tablet formulations) 3, 1
• This higher iron density compared to ferrous sulfate (20% elemental iron) or ferrous gluconate (12% elemental iron) allows for smaller pill burden in children 1

Standard Treatment Dosing

For confirmed iron-deficiency anemia:

• 3 mg/kg/day of elemental iron is the standard therapeutic dose 1, 2
• For a 10 kg child, this equals 30 mg elemental iron daily, which translates to approximately 90 mg of ferrous fumarate salt 1
• Divide into 1-2 doses throughout the day for better tolerability 1

Practical example:

• A 15 kg child requires 45 mg elemental iron daily = approximately 135 mg ferrous fumarate salt per day 1

Administration Guidelines to Maximize Absorption

• Give between meals (on an empty stomach) whenever possible, as food reduces iron absorption by up to 50% 1, 2
• Specifically avoid administration within 2 hours before or 1 hour after meals 1
• Do not give with tea, coffee, or dairy products, which significantly inhibit iron absorption 3
• Avoid concurrent administration with aluminum-based phosphate binders, which reduce iron absorption 1

Formulation Selection by Age

• Liquid preparations are preferred for infants and young children who cannot swallow tablets 1
• Ferrous fumarate liquid contains approximately 45 mg elemental iron per 5 mL 3
• Tablets or capsules may be used in older children who can swallow them reliably 1

Treatment Duration and Monitoring

Initial phase:

• Continue therapy for 4 weeks, then recheck hemoglobin 2
• An increase of ≥1 g/dL in hemoglobin confirms adequate response and iron-deficiency anemia diagnosis 2

Continuation phase:

• If response is adequate, continue for an additional 2 months (total ~3 months) to replenish iron stores 2
• After completing the full course, recheck hemoglobin and reassess approximately 6 months later 2

Managing Side Effects and Non-Response

If gastrointestinal side effects occur:

• Reduce to smaller, more frequent doses rather than discontinuing therapy 1
• Consider alternate-day dosing, which may improve tolerance while maintaining efficacy 3
• Start with a lower dose and gradually increase to target dose over several days 1
• Mild GI symptoms (nausea, constipation) should not prompt immediate discontinuation 1, 2

If no response after 4 weeks despite confirmed adherence:

• Obtain further laboratory evaluation including MCV, RDW, and serum ferritin 2
• Consider switching to intravenous iron if malabsorption is suspected 3
• Rule out ongoing blood loss or other causes of anemia 2

Important Safety Considerations

• Systemic iron toxicity with hepatocellular damage has been reported with excessive iron administration in pediatric patients 1, 2
• Strict adherence to weight-based dosing (3 mg/kg/day elemental iron) is essential to prevent toxicity 1
• Keep iron supplements out of reach of children, as accidental overdose can be fatal 1

Bioavailability Considerations in Iron-Deficient Children

• Recent isotope studies show that iron-deficient children may absorb iron from ferrous fumarate only 30% as well as from ferrous sulfate, though this remains controversial 4, 5
• In iron-replete children, ferrous fumarate and ferrous sulfate show equivalent absorption 5
• For severely iron-deficient children who fail to respond, consider switching to ferrous sulfate or increasing the ferrous fumarate dose 4
• Clinical efficacy studies demonstrate that ferrous fumarate successfully treats and prevents iron deficiency when dosed appropriately 4, 6

Dietary Counseling

• Always provide concurrent dietary counseling to address underlying inadequate iron intake 2
• Encourage iron-rich foods and foods that enhance iron absorption (vitamin C-rich foods) 2