How to manage iron deficiency anemia in a 30-week pregnant woman with low ferritin (8) and iron saturation (17)?

Management of Iron Deficiency Anemia in a 30-Week Pregnant Woman

For a 30-week pregnant woman with ferritin of 8 and iron saturation of 17%, oral iron supplementation at a dose of 60-120 mg of elemental iron daily is recommended as first-line treatment, with consideration of IV iron if there is poor response or intolerance to oral therapy. 1

Diagnosis Assessment

The laboratory values clearly indicate iron deficiency anemia:

• Ferritin of 8 ng/mL (significantly below the threshold of 30 μg/L)
• Iron saturation of 17% (below the threshold of 20%)
• Third trimester of pregnancy (30 weeks)

These values meet the diagnostic criteria for iron deficiency anemia in pregnancy according to the American College of Obstetricians and Gynecologists, with ferritin <30 ng/mL and transferrin saturation <20% 1, 2.

Treatment Algorithm

First-Line Treatment:

• Oral Iron Therapy:
  • Dosage: 60-120 mg of elemental iron daily 1
  • Common formulation: Ferrous sulfate 325 mg (contains approximately 65 mg elemental iron)
  • Administration: Take between meals or at bedtime to optimize absorption 3
  • Duration: Continue until delivery and postpartum until iron stores are replenished (ferritin >30 μg/L) 1

Management of Side Effects:

• If gastrointestinal side effects occur (nausea, constipation):
  • Consider alternate-day dosing
  • Take with small amount of food if necessary
  • Consider stool softeners for constipation

Monitoring Response:

• Check hemoglobin and ferritin levels in 2-4 weeks to assess response
• Target hemoglobin increase of at least 1 g/dL within 2-3 weeks 1

Second-Line Treatment (if indicated):

• Intravenous Iron Therapy should be considered if:

  • Poor response to oral iron (hemoglobin increase <1 g/dL after 2-3 weeks)
  • Intolerance to oral iron despite dose adjustments
  • Severe anemia (Hb <7 g/dL)
  • Need for rapid correction (advanced pregnancy at 30 weeks) 1, 4

• IV Iron Options:

  • Ferric carboxymaltose: Safe during pregnancy, especially in second and third trimesters 5
  • Iron sucrose: Well-studied in pregnancy with good safety profile 6

Special Considerations

1. Severity Assessment:

   • At 30 weeks gestation, anemia is defined as Hb <10.5 g/dL 1
   • If hemoglobin is severely low (<7 g/dL), consider blood transfusion 1

2. Timing Considerations:

   • At 30 weeks, approximately 80% of fetal iron accrues in the last trimester, making prompt treatment essential 1
   • The third trimester is a critical period for fetal iron accumulation

3. Post-Treatment Follow-up:

   • Continue iron supplementation postpartum
   • Monitor hemoglobin and ferritin 6-8 weeks postpartum
   • Studies show that prenatal iron supplementation reduces iron deficiency at 6 months postpartum 7

Clinical Pearls and Pitfalls

• Pearl: Low-dose iron (20 mg/day) has been shown to effectively prevent iron deficiency anemia with fewer side effects, but for treatment of established deficiency, higher doses are needed 7

• Pitfall: Avoid excessive iron supplementation without monitoring, as this can lead to oxidative stress during pregnancy 3

• Pearl: IV iron should be strongly considered given the advanced gestational age (30 weeks) and very low ferritin (8), as this allows for more rapid correction of iron stores 4

• Pitfall: Do not delay treatment while investigating the cause of iron deficiency in pregnancy, as the physiological demands of pregnancy often exceed dietary iron intake 1, 2

The benefits of treating iron deficiency anemia in pregnancy outweigh the risks, as untreated anemia is associated with adverse maternal and fetal outcomes including preterm delivery, low birth weight, and postpartum anemia 3, 2.