Treatment for Iron Deficiency Anemia in Third Trimester Pregnancy with Ferritin of 8
For a pregnant patient in the third trimester with a ferritin level of 8, oral iron supplementation at a dose of 60-120 mg of elemental iron daily is recommended for treatment of iron deficiency anemia. 1
Diagnosis and Assessment
A ferritin level of 8 μg/L in the third trimester of pregnancy clearly indicates iron deficiency anemia, as it is well below the threshold of 30 μg/L used to diagnose iron deficiency 1, 2. This requires prompt treatment to prevent adverse maternal and fetal outcomes.
- Confirm the diagnosis with hemoglobin measurement
- Third trimester anemia is defined as Hb <10.5 g/dL 1
- Assess severity of anemia:
- Mild: Hb 10-10.5 g/dL
- Moderate: Hb 7-9.9 g/dL
- Severe: Hb <7 g/dL
Treatment Approach
Oral Iron Therapy (First-line)
- Dosage: 60-120 mg of elemental iron daily 3, 1
- Formulation: Ferrous sulfate is the most commonly used and FDA-approved form 4
- Administration: Take between meals or at bedtime to maximize absorption 5
- If GI side effects occur, may take with meals (though this reduces absorption)
- Duration: Continue treatment until hemoglobin normalizes, then reduce to maintenance dose of 30 mg/day 3, 1
- Monitoring: Repeat hemoglobin after 4 weeks of treatment to assess response 3
- Expect hemoglobin to increase by approximately 1 g/dL after 4 weeks of compliant therapy
Management of Side Effects
Common side effects include:
- Nausea (29-63%)
- Constipation (4-29%)
- Abdominal discomfort
- Diarrhea 1
Side effect management:
- Consider taking with food if side effects are significant
- Stool softeners for constipation
- Consider alternate-day dosing if daily dosing is not tolerated 6
When to Consider IV Iron
Consider intravenous iron supplementation if:
- Oral iron is not tolerated due to side effects
- No improvement in hemoglobin after 4 weeks of oral therapy
- Moderate to severe anemia (Hb <9 g/dL) in late third trimester
- Malabsorption conditions are present 1, 2
Severe Anemia Management
For severe anemia (Hb <7 g/dL):
- Consider blood transfusion, especially with hemodynamic instability
- Follow with IV iron supplementation to replenish stores
- Monitor hemoglobin and ferritin 2-4 weeks post-treatment 1
Expected Outcomes and Follow-up
- Aim to normalize hemoglobin for gestational age
- Continue iron supplementation through delivery and postpartum period
- Recheck ferritin levels 4-6 weeks postpartum to ensure adequate repletion of iron stores 3
Important Considerations
- Iron deficiency in the third trimester can lead to adverse maternal and fetal outcomes including preterm delivery and low birth weight 5
- Without treatment, maternal iron stores will remain depleted postpartum 7
- Approximately 80% of fetal iron accrues in the last trimester, making treatment during this period particularly important 1
- Even with treatment, full restoration of iron stores may take 2-3 months 3
Remember that iron supplementation is safe during pregnancy when taken as directed, and the benefits of treating iron deficiency anemia outweigh the potential side effects of supplementation 1, 4.