What is the recommended dosing of ferrous (iron) fumarate for pediatric patients?

Ferrous Fumarate Dosing for Pediatric Patients

For pediatric patients, ferrous fumarate should be dosed at 2 to 3 mg/kg/day of elemental iron, divided into 2 to 3 doses per day, administered on an empty stomach for optimal absorption. 1

Elemental Iron Content

• Ferrous fumarate contains 108 mg of elemental iron per 325 mg tablet, making it the most iron-dense oral preparation compared to ferrous sulfate (65 mg elemental iron per 325 mg) or ferrous gluconate (35 mg elemental iron per 325 mg). 1
• This higher elemental iron content allows for smaller pill burden when calculating pediatric doses. 1

Standard Dosing Regimen

General Pediatric Dosing

• The standard dose is 2 to 3 mg/kg/day of elemental iron (not total ferrous fumarate salt weight), divided into 2 to 3 doses throughout the day. 1
• For a 10 kg child, this translates to 20-30 mg of elemental iron daily, which equals approximately 60-90 mg of ferrous fumarate salt per day. 1

Treatment of Iron Deficiency Anemia

• For treatment of confirmed iron deficiency anemia, use 3 mg/kg/day of elemental iron given between meals to maximize absorption. 2
• Continue treatment for 4 weeks, then recheck hemoglobin; if hemoglobin increases by ≥1 g/dL, continue for 2 additional months. 2

Administration Guidelines

Timing and Food Interactions

• Iron should be administered on an empty stomach (not with meals) as food reduces iron absorption by up to 50%. 1
• Specifically, avoid giving iron within 2 hours before or 1 hour after meals. 1
• Aluminum-based phosphate binders also reduce iron absorption and should be separated from iron dosing. 1

Formulation Considerations

• Liquid iron preparations are more appropriate for young pediatric patients than solid dose forms. 1
• Ferrous fumarate, ferrous sulfate, and ferrous gluconate are all acceptable ionic iron salts that provide known amounts of elemental iron. 1

Important Clinical Caveats

Absorption Differences in Children

• Iron-deficient children may absorb iron from ferrous fumarate less efficiently than from ferrous sulfate, with relative bioavailability of only 30% compared to ferrous sulfate in some studies. 3
• This reduced absorption may be related to lower gastric acid secretion in children or differences in dissolution rates. 3
• Despite lower absorption, ferrous fumarate-fortified foods have successfully prevented iron deficiency in iron-replete infants. 3

Tolerance and Side Effects

• If gastrointestinal side effects occur, reduce to smaller, more frequent doses or consider alternate-day dosing rather than discontinuing therapy. 1
• Mild gastrointestinal symptoms (nausea, vomiting, diarrhea) should not necessarily prompt discontinuation. 2
• Starting with a lower dose and gradually increasing to target may improve tolerance. 1

Monitoring

• Recheck hemoglobin after 4 weeks of treatment; if no response despite compliance, further evaluation with MCV, RDW, and serum ferritin is needed. 2
• Systemic iron toxicity with hepatocellular damage has been reported with excessive iron administration in pediatric patients, emphasizing the importance of proper dosing. 2

Alternative Formulations

• Microencapsulated ferrous fumarate sprinkles (80 mg elemental iron once daily) have shown similar efficacy to ferrous sulfate drops (40 mg elemental iron in divided doses) for treating anemia in infants aged 6-18 months, with potentially better adherence. 4