What is the recommended treatment for a 24-week pregnant woman, gravida 7 (G7), with presumed iron deficiency anemia?

Treatment of Presumed Iron Deficiency Anemia at 24 Weeks Gestation

Start oral iron supplementation at 60-120 mg of elemental iron daily as first-line treatment for this G7 patient at 24 weeks gestation with presumed iron deficiency anemia. 1, 2

Diagnostic Confirmation

Before initiating treatment, confirm the diagnosis with:

• Hemoglobin < 10.5-11.0 g/dL is diagnostic of anemia in the second trimester 2
• If hemoglobin ≥ 10.0 g/dL with mildly low or normal mean corpuscular volume (MCV), presume iron deficiency anemia and proceed with empiric oral iron therapy 2
• Serum ferritin < 30 μg/L confirms iron deficiency, but remember that ferritin is an acute phase reactant and may be falsely elevated during inflammation, potentially masking true iron deficiency 3, 1
• Do not confuse physiologic anemia of pregnancy (hemodilution) with true iron deficiency anemia 3, 1

First-Line Treatment Protocol

Oral iron supplementation is the recommended first-line treatment:

• Prescribe 60-120 mg/day of elemental iron 4, 1, 2
• Recent evidence suggests intermittent dosing (not daily) is as effective as daily or twice-daily dosing with fewer gastrointestinal side effects 2
• Provide dietary counseling to increase consumption of iron-rich foods and foods that enhance iron absorption 1
• Common side effects include nausea, constipation, diarrhea, darkening of stool/urine, and teeth staining—these are self-limited and transient 4

Monitoring Response

Reassess after 4 weeks of treatment:

• Adequate response is defined as hemoglobin increase ≥ 1 g/dL or hematocrit increase ≥ 3% 1
• If anemia persists despite documented compliance with oral iron, obtain additional laboratory tests including MCV, red cell distribution width (RDW), and serum ferritin 1

When to Consider Intravenous Iron

Intravenous iron is preferred over oral iron when:

• Patient cannot tolerate oral iron due to gastrointestinal side effects 2
• Patient cannot absorb oral iron 2
• Patient does not respond to oral iron after 4 weeks of adequate compliance 2
• Intravenous iron sucrose is safe after the first trimester and produces better hematological response than oral iron 5, 6
• With contemporary IV iron formulations, allergic reactions are rare 2
• Be aware that severe hypersensitivity reactions including circulatory failure and shock can occur with parenteral iron products, potentially causing fetal bradycardia, especially during the second and third trimester 5

Critical Pitfalls to Avoid

In women of African, Mediterranean, or Southeast Asian ancestry, mild anemia unresponsive to iron therapy may indicate thalassemia minor or sickle cell trait rather than iron deficiency 3, 1

If hemoglobin is < 10.0 g/dL (moderate anemia) or if MCV is very low or elevated (macrocytic), further investigation is required before empiric iron treatment 2

At 24 weeks gestation, there is adequate time for oral iron to work (requires 4 weeks for response), so intravenous iron is not necessary as first-line unless oral iron is contraindicated or not tolerated 3, 2

Guideline Context

The American College of Obstetricians and Gynecologists (ACOG) recommends screening all pregnant women and treating iron deficiency anemia with supplemental iron 3

The Centers for Disease Control and Prevention (CDC) recommends screening and low-dose iron supplementation for all pregnant women 3

Note that the U.S. Preventive Services Task Force (USPSTF) found insufficient evidence to determine the balance of benefits and harms of routine iron supplementation during pregnancy, but this does not apply to treatment of confirmed anemia 4, 1