What is the appropriate management for a 17-year-old female with anemia (low hemoglobin and hematocrit), leukopenia (low white blood cell count), and slightly low mean corpuscular volume?

Management of Microcytic Anemia with Leukopenia in a 17-Year-Old Female

This patient requires immediate iron studies (serum ferritin and transferrin saturation) to confirm iron deficiency anemia, followed by hematology consultation given the concurrent leukopenia affecting two cell lines. 1, 2

Initial Diagnostic Approach

Complete the iron deficiency workup immediately:

• Serum ferritin is the single most powerful test for iron deficiency 1, 2, 3
  • Ferritin <30 μg/L confirms iron deficiency in the absence of inflammation 1, 2, 3
  • Ferritin <15 μg/L is diagnostic of iron deficiency 1, 3
• Transferrin saturation (TSAT) to assess iron available for erythropoiesis 1, 2, 3
  • TSAT <15-20% supports iron deficiency 2, 3
  • TSAT is less affected by inflammation than ferritin 1, 3
• Absolute reticulocyte count to evaluate bone marrow response 1, 2
  • Low or normal reticulocyte count indicates impaired red cell production 2, 3
• Vitamin B12 and folate levels to exclude combined deficiency 1, 2

Critical Red Flag: Multi-Lineage Cytopenia

The combination of anemia AND leukopenia (WBC 3.6 K/uL) represents abnormalities in two cell lines and mandates hematology consultation. 1, 2

• Abnormalities in two or more cell lines should be evaluated carefully and likely warrant discussion with a hematologist 1
• This pattern raises concern for bone marrow dysfunction beyond simple nutritional deficiency 1
• Do not presume iron deficiency alone explains both cytopenias without excluding more serious pathology 1

Interpretation of Current Laboratory Values

The microcytic pattern (MCV 77.6 fL, MCH 25.8 pg) strongly suggests iron deficiency:

• Low MCV typically indicates deficiencies of iron, folic acid, vitamin B12, or inherited hemoglobin synthesis disorders 1
• Low MCH is a reliable marker of iron deficiency and indicates hypochromic anemia 3
• The combination of low hemoglobin (10.5 g/dL), low MCV, and low MCH makes iron deficiency the most likely diagnosis 3, 4

However, normal hemoglobin and hematocrit do not exclude iron deficiency:

• These parameters decrease only when severe iron depletion is present 5
• Iron-depleted individuals can be missed if only CBC is checked without iron studies 5

Age and Gender-Specific Considerations

This 17-year-old female is at particularly high risk for iron deficiency:

• Menstrual blood loss is a major risk factor for iron deficiency in adolescent females 1
• Heavy menstrual bleeding should be specifically assessed 1
• Dietary history is important, particularly restrictive diets (no red meat, vegetarian, vegan) 1
• However, do not presume borderline deficient diets as the sole cause without full investigation 1, 2

Management Algorithm

Step 1: Confirm iron deficiency with serum ferritin and TSAT 2, 3

Step 2: If iron deficiency confirmed (ferritin <30 μg/L, TSAT <20%):

• Initiate oral iron supplementation: ferrous sulfate 325 mg (65 mg elemental iron) 1-3 times daily between meals 3
• Expect hemoglobin increase of approximately 1-2 g/dL every 2-4 weeks 3
• Continue iron for 3-6 months after hemoglobin normalizes to replenish stores 3
• Check hemoglobin, reticulocytes, and iron studies after 4-8 weeks 3

Step 3: Investigate underlying cause of iron deficiency:

• Detailed menstrual history (duration, frequency, heaviness) 1
• Dietary assessment for inadequate iron intake 1
• Consider gastrointestinal evaluation if menstrual losses and diet do not explain severity 1

Step 4: Mandatory hematology referral for the leukopenia:

• The concurrent leukopenia requires evaluation independent of iron deficiency 1, 2
• Bone marrow biopsy may be necessary if no clear explanation emerges 1

Common Pitfalls to Avoid

• Do not accept ferritin alone in patients with inflammation; use TSAT to confirm iron deficiency 2, 3
• Do not rely on MCV alone, as iron deficiency can present with normal MCV in early stages 3
• Do not overlook the leukopenia—this is not explained by iron deficiency alone and requires separate evaluation 1, 2
• Do not presume dietary insufficiency as the sole cause without confirming with iron studies and excluding other pathology 1, 2