What is the next step in management for a 15‑year‑old female with iron‑deficiency anemia?

Next Step: Start Empiric Oral Iron Therapy Immediately

Begin oral iron supplementation at 60–120 mg elemental iron daily, taken between meals, and recheck hemoglobin in 4 weeks to confirm the diagnosis. 1

Rationale for Empiric Treatment

This 15-year-old female presents with classic laboratory findings of iron-deficiency anemia:

• Microcytic anemia (MCV 66.2 fL, normal ~80–100) with marked hypochromasia (2+) and microcytosis (2+) 2
• Elevated RBC count (6.03, above normal ~4.2–5.4 for females) combined with low MCV is highly suggestive of iron deficiency rather than thalassemia trait 1
• Elevated RDW (16.6%, above normal ≤14%) strongly favors iron deficiency over thalassemia trait, which typically shows normal RDW 1, 2
• Low serum iron (45 µg/dL, normal ~50–170) confirms inadequate iron availability 2

The CDC permits a presumptive diagnosis of iron-deficiency anemia in otherwise healthy adolescent girls who are not acutely ill, allowing immediate initiation of empiric therapy without waiting for additional confirmatory tests. 1

Treatment Protocol

Dosing and Administration

• Prescribe 60–120 mg elemental iron daily (e.g., ferrous sulfate 325 mg contains 65 mg elemental iron; give 1–2 tablets daily) 1, 2
• Administer between meals to maximize absorption 1, 2
• Provide dietary counseling emphasizing heme iron sources (meat, poultry, fish with 15–35% bioavailability) and vitamin C co-ingestion to enhance non-heme iron absorption 1, 2

Confirmation of Diagnosis at 4 Weeks

• Recheck hemoglobin after 4 weeks of therapy 1, 2
• A rise of ≥1 g/dL hemoglobin (or ≥3% hematocrit) confirms iron-deficiency anemia and validates the empiric approach 1, 2
• If confirmed, continue iron for an additional 2–3 months to replenish iron stores 1, 2

Final Monitoring

• Reassess hemoglobin approximately 6 months after completing therapy 1
• Consider annual screening if ongoing risk factors persist (heavy menstrual bleeding, restrictive diet, athletic activity) 1

When to Obtain Additional Testing

If hemoglobin fails to rise ≥1 g/dL after 4 weeks despite documented adherence, obtain: 1

• Serum ferritin: <15 µg/L confirms iron deficiency; ≥15 µg/L suggests alternative etiology 1, 2
• C-reactive protein (CRP): to detect inflammation that can falsely elevate ferritin and mask iron deficiency 1
• Transferrin saturation: <20% indicates iron-restricted erythropoiesis 1
• Hemoglobin electrophoresis: only if microcytosis persists with normal iron studies, especially in patients of African, Mediterranean, or Southeast Asian ancestry, to detect thalassemia trait 1

Key Risk Factors to Assess

Evaluate for common causes of iron deficiency in adolescent females: 1, 2

• Heavy or prolonged menstrual bleeding (most common cause in this population)
• Low dietary iron intake (vegetarian/vegan diets, restrictive eating)
• High-impact or endurance sports participation
• Prior history of iron-deficiency anemia

Critical Pitfalls to Avoid

• Do not delay iron therapy while awaiting ferritin results; the 4-week hemoglobin response serves as diagnostic confirmation 1, 2
• Do not order hemoglobin electrophoresis now; with RDW >14% and low iron, this pattern indicates iron deficiency, not thalassemia trait 2
• Do not stop iron when hemoglobin normalizes; an additional 2–3 months is required to replenish stores 1, 2
• Do not assume all microcytic anemia is iron deficiency; thalassemia trait can coexist, but the elevated RDW here points to iron deficiency 1
• Do not rely solely on hemoglobin and hematocrit; these fall only after severe iron depletion 1