What is the next step for a patient with severe microcytic anemia (low Mean Corpuscular Volume (MCV)) and a hemoglobin level indicating severe anemia?

Management of Severe Microcytic Anemia with Hemoglobin 6.2 g/dL

Blood transfusion is the immediate next step for this patient with severe anemia (hemoglobin 6.2 g/dL), followed by oral iron supplementation once stabilized. 1

Immediate Management: Transfusion Threshold

• Packed red cell transfusions are indicated when hemoglobin decreases to less than 7.5 g/dL and/or there are clinical symptoms, which this patient clearly meets with pallor, fatigue, and hemoglobin of 6.2 g/dL 1
• Transfuse 2-3 units of packed red blood cells to address the acute anemia while avoiding complications from volume overload 1
• Each 400 mL unit should increase hemoglobin by approximately 1.5 g/dL 1
• This is especially critical if the patient has comorbidities, older age, or ischemic heart disease 1

Concurrent Diagnostic Workup During Stabilization

While preparing for transfusion, obtain:

• Serum ferritin as the most specific test for iron deficiency, with levels <30 μg/L indicating low iron stores, though a cutoff of 45 μg/L provides optimal sensitivity and specificity 2, 3
• Transferrin saturation (TSAT), which is more sensitive for detecting iron deficiency than hemoglobin alone 2, 3
• Red cell distribution width (RDW): elevated RDW (>14.0%) with low MCV strongly suggests iron deficiency anemia rather than thalassemia trait 2, 3
• Complete blood count with reticulocyte count, CRP, and peripheral smear 1

Post-Transfusion Treatment: Oral Iron Supplementation

Once the patient is stabilized:

• Start ferrous sulfate 200 mg (65 mg elemental iron) three times daily for at least three months after correction of anemia to replenish iron stores 2, 3
• Add ascorbic acid (vitamin C) to enhance iron absorption 2, 3
• Alternative formulations include ferrous gluconate or ferrous fumarate if gastrointestinal side effects occur 2, 3
• A good response is defined as hemoglobin rise ≥10 g/L (≥1 g/dL) within 2 weeks, confirming iron deficiency 2, 3

Monitoring Strategy

• Monitor hemoglobin concentration and red cell indices at three-monthly intervals for one year, then after a further year 2, 3
• Expect hemoglobin increase of at least 2 g/dL within 4 weeks of starting oral iron 2
• Provide additional oral iron if hemoglobin or MCV falls below normal 2, 3

Critical Pitfalls to Avoid

• Do not delay transfusion to "work up" the anemia first—hemoglobin of 6.2 g/dL with symptoms requires immediate correction 1
• Do not start with oral iron alone in severe anemia (Hb <7.5 g/dL), as this patient needs rapid correction of oxygen-carrying capacity 1
• Do not assume all microcytic anemia is iron deficiency: if ferritin is normal or elevated (>20 μg/L) despite microcytosis, consider genetic disorders of iron metabolism or anemia of chronic disease 2, 3
• Do not overlook combined deficiencies, as iron deficiency can coexist with B12 or folate deficiency 2
• Bone marrow biopsy is not indicated as a next step in straightforward microcytic anemia with severe symptoms—reserve this for refractory cases after failed iron therapy or when the diagnosis remains unclear 1

Why Not Start with Oral Iron Alone?

The hemoglobin of 6.2 g/dL represents severe, symptomatic anemia requiring urgent correction. While oral iron is the definitive treatment for iron deficiency anemia, it takes weeks to significantly raise hemoglobin levels 2, 3. The patient's symptoms (pallor, fatigue) and critically low hemoglobin create immediate risk, particularly if there are underlying cardiac conditions or the patient is elderly 1.