This is a Phase 3, randomized, open-label, multicenter, study in male and female pediatric subjects (2 years to <18 years of age) with IDA, or felt by their clinician to be at risk of developing IDA. This study allows for enrollment of subjects with IDA regardless of etiology, except for CKD subjects (pediatric CKD subjects are being studied in a separate ferumoxytol protocol).

Subjects will be randomized to treatment in a 2:1 ratio (ferumoxytol: iron sucrose) and stratified by age group (2 to <6 years; 6 to <12 years; and 12 to <18 years). Subjects will receive one of the following treatment regimens:

• Ferumoxytol: 7 mg Fe/kg IV (maximum 510 mg/dose) x 2 doses, the first dose administered on Day 1 and the second 2 to 8 days later.

OR

• Iron sucrose (Venofer®): 4 mg Fe/kg IV (maximum 200 mg/dose) x 5 doses, the first dose on Day 1 and subsequent doses administered at least once per week and up to 3 times/week. All subjects will be monitored at the study site through at least 1 hour after the completion of each infusion of study drug. Assessment of blood Hgb concentrations, adverse events, and other safety assessments will be performed through study Week 5.

Inclusion Criteria:

1. Male or female 2 years to <18 years of age at time of consent

2. Has IDA defined as:

   1. Hemoglobin (Hgb) <11.0 g/dL AND

   2. Any one or more of the following:

      • Transferrin saturation (TSAT) <20%
      • ferritin <100 ng/mL

3. Documented history of unsatisfactory oral iron therapy or in whom oral iron cannot be tolerated, or for whom oral iron is considered medically inappropriate

Exclusion Criteria:

1. Known hypersensitivity reaction to any component of ferumoxytol or iron sucrose
2. History of allergy to intravenous (IV) iron
3. History of ≥2 clinically significant drug allergies
4. Subjects with CKD (defined as eGFR of <60 mL/min/1.73 m2 or a requirement for chronic hemodialysis or peritoneal dialysis during Screening)
5. Low systolic blood pressure (BP) (age 1 to 9 years <70 + [age in years x 2] mmHg, age 10 to 17 years <90 mmHg)
6. Hgb ≤7.0 g/dL
7. Serum ferritin level >600 ng/mL