In a 15-year-old female with mild anemia (hemoglobin 11.8 g/dL, hematocrit 35.2%), normal AST, normal thyroid function, normal red‑cell indices, and platelet count 26.9 ×10^9/L, what laboratory studies should be ordered and what medication should be started?

Immediate Laboratory Workup and Treatment for Adolescent Female with Mild Anemia

Order a complete iron panel (serum ferritin, transferrin saturation, serum iron, and TIBC) immediately, and start oral iron supplementation with 60–120 mg elemental iron daily while awaiting results. 1, 2

Critical Laboratory Tests Required

First-Line Iron Studies (Order All Together)

• Serum ferritin is the single most useful test; levels <30 µg/L confirm iron deficiency in the absence of inflammation 1, 2
• Transferrin saturation <15–16% supports iron deficiency and is less affected by acute inflammation than ferritin 1, 2
• C-reactive protein (CRP) must be measured concurrently because ferritin rises as an acute-phase reactant; inflammation can falsely elevate ferritin and mask true iron deficiency 2
• Reticulocyte count to assess bone marrow response; a low or inappropriately normal count indicates inadequate compensation for anemia 2

Why These Labs Are Essential in This Patient

• Her hemoglobin of 11.8 g/dL meets WHO criteria for mild anemia in females ≥15 years (anemia defined as Hb <12 g/dL) 2
• Her MCH of 26.9 pg is low and represents the most sensitive early marker of iron deficiency, reflecting reduced hemoglobin content in newly produced red cells 2
• Her MCHC of 33.5 g/dL is low, confirming hypochromia and indicating red cells contain less hemoglobin per unit volume than normal 2
• Her RDW of 14.3% is at the upper limit of normal, suggesting increased red cell size variation consistent with early iron-deficient erythropoiesis 2
• Normal CBC parameters alone do not exclude iron deficiency; individuals can have normal hemoglobin/hematocrit with depleted iron stores that will progress to overt anemia if untreated 3

Medication: Start Oral Iron Immediately

Dosing for Adolescent Females

• Prescribe 60–120 mg elemental iron daily (one to two 60-mg iron tablets) taken between meals to maximize absorption 1
• Common formulations: ferrous sulfate 325 mg contains ~65 mg elemental iron 2

Rationale for Empiric Treatment

• In adolescent females with mild anemia and low MCH/MCHC, iron deficiency is the most likely diagnosis and affects 7.8 million adolescent females in the United States, with prevalence exceeding 50% in some cohorts due to menstrual blood loss, rapid growth, and inadequate dietary iron intake (recommended 15 mg/day) 2
• A good response to iron therapy (hemoglobin rise ≥1 g/dL within 4 weeks) confirms iron-deficiency anemia even if initial iron studies are equivocal 1
• Starting treatment immediately prevents progression from Stage 2 (iron-deficient erythropoiesis) to Stage 3 (frank iron-deficiency anemia) 2

Monitoring and Follow-Up Algorithm

4-Week Recheck (Critical Decision Point)

1. Repeat hemoglobin/hematocrit at 4 weeks 1

2. If hemoglobin increases ≥1 g/dL or hematocrit ≥3%: diagnosis of iron-deficiency anemia is confirmed 1

   • Continue iron therapy for 3 more months (total 4 months) to replenish body iron stores 1, 2
   • Reinforce dietary counseling on iron-rich foods 1
   • Recheck hemoglobin/hematocrit at end of treatment, then again 6 months later 1

3. If hemoglobin does NOT rise despite documented adherence: 1

   • Screen for celiac disease with tissue transglutaminase (tTG) antibodies; malabsorption causes ~5% of iron-deficiency anemia 2
   • Evaluate for gastrointestinal blood loss: detailed history of NSAID use, GI symptoms 2
   • Consider hemoglobin electrophoresis if patient has African, Mediterranean, or Southeast Asian ancestry to rule out thalassemia trait 1, 2

Additional Diagnostic Considerations

Assess Menstrual Blood Loss

• Heavy menstrual bleeding is the leading cause of iron deficiency in adolescent females 2
• If menstrual losses appear excessive, gynecologic referral may be warranted 2

When Iron Studies Return Normal

• If ferritin >30 µg/L and transferrin saturation >16% with normal CRP, consider alternative diagnoses: 2
  • Vitamin B12 or folate deficiency: order serum B12 and folate levels
  • Hemoglobinopathies (thalassemia trait): order hemoglobin electrophoresis, especially in at-risk ethnic groups
  • Anemia of chronic disease: evaluate for underlying inflammatory conditions

Common Pitfalls to Avoid

• Do not rely on ferritin alone without CRP; inflammation falsely elevates ferritin and masks true iron deficiency 2
• Do not assume normal MCV excludes iron deficiency; MCH drops before MCV in early deficiency 1, 2
• Do not limit evaluation to CBC alone; iron studies are essential because individuals can have normal hemoglobin with depleted iron stores 3
• Do not stop iron therapy when hemoglobin normalizes; continue for 3–6 months to replenish body stores, as anemia recurs in >50% of patients within one year if stores are not repleted 2

Dietary Counseling (Concurrent with Iron Therapy)

• Encourage iron-rich foods: red meat, poultry, fish, fortified cereals, beans, lentils 1
• Enhance absorption with vitamin C-rich foods (citrus, tomatoes) 1
• Avoid excessive cow's milk (>24 oz/day) and high-fiber intake that impairs iron absorption 1, 4