What is the appropriate management for a patient with microcytic hypochromic anemia, characterized by low Hemoglobin (Hgb), low Hematocrit (Hct), low Mean Corpuscular Volume (MCV), low Mean Corpuscular Hemoglobin (MCH), low Mean Corpuscular Hemoglobin Concentration (MCHC), elevated Red Cell Distribution Width (RDW), and a normal Platelet (Plt) count?

Management of Severe Microcytic Hypochromic Anemia

Immediate Treatment Recommendation

Start oral ferrous sulfate 200 mg three times daily immediately and continue for at least 3 months after hemoglobin correction to replenish iron stores. 1

Your laboratory values (Hgb 6.4 g/dL, MCV 71 fL, MCH 19.1 pg, MCHC 26.8 g/dL, RDW 19.0%) indicate severe microcytic hypochromic anemia, most likely iron deficiency anemia given the markedly elevated RDW (>14.0%), which distinguishes this from thalassemia minor. 1

Diagnostic Confirmation Required

Before proceeding with treatment, obtain serum ferritin immediately as it is the single most useful marker for confirming iron deficiency: 1, 2, 3

• Ferritin <15 μg/L: Confirms absent iron stores (specificity 99%) 3
• Ferritin <30 μg/L: Indicates low body iron stores 1, 3
• Ferritin <45 μg/L: Optimal sensitivity/specificity cutoff, especially if inflammation present 1, 3
• Ferritin >150 μg/L: Makes absolute iron deficiency unlikely 3

Add transferrin saturation if ferritin appears falsely normal due to suspected inflammation, as this is more sensitive than hemoglobin alone for detecting iron deficiency. 1, 2

Treatment Protocol

First-Line Oral Iron Therapy

Ferrous sulfate 324 mg tablets (containing 65 mg elemental iron) two to three times daily without crushing or chewing. 4 Alternative formulations include ferrous gluconate or ferrous fumarate if not tolerated. 1

• Add ascorbic acid to enhance iron absorption 1
• Expected response: Hemoglobin rise ≥10 g/L (≥1 g/dL) within 2 weeks confirms iron deficiency 1, 2
• Continue therapy for 3 months total after anemia correction to replenish stores 1, 2

If No Response to Oral Iron (After 2-4 Weeks)

Consider the following causes of treatment failure: 1

• Non-compliance with medication
• Ongoing blood loss (most common)
• Malabsorption (celiac disease, inflammatory bowel disease)
• Rare genetic disorders (IRIDA, sideroblastic anemia)

Switch to intravenous iron if malabsorption confirmed, expecting hemoglobin increase of at least 2 g/dL within 4 weeks. 1, 2

Critical Investigation for Underlying Cause

This severe anemia demands immediate investigation for the source of iron loss: 1

High-Priority Investigations

• Gastrointestinal evaluation: Fast-track GI referral warranted for non-menstruating women with Hb <100 g/L or men with Hb <110 g/L 1
• Evaluate for GI blood loss: History of melena, hematochezia, or occult bleeding 1
• Screen for celiac disease if malabsorption suspected 1
• Assess menstrual blood loss in premenopausal women (most common cause) 1

Additional Testing if Iron Studies Normal

Order hemoglobin electrophoresis if microcytosis persists with normal iron studies, appropriate ethnic background, or MCV disproportionately low relative to anemia degree to exclude thalassemia. 1, 3

Consider genetic testing for disorders (SLC11A2, STEAP3, SLC25A38, ALAS2, ABCB7) if extreme microcytosis (MCV <70 fL) or family history present. 1

Monitoring Protocol

• Recheck hemoglobin and red cell indices at 2 weeks to confirm response 1, 2
• Monitor at 3-monthly intervals for one year, then annually 1
• Provide additional oral iron if hemoglobin or MCV falls below normal 1
• Monitor for iron overload if multiple transfusions or long-term therapy required 1

Critical Pitfalls to Avoid

• Do not assume all microcytic anemia is iron deficiency: Anemia of chronic disease, thalassemia, and sideroblastic anemia must be differentiated to avoid unnecessary iron therapy 1
• Do not overlook combined deficiencies: Iron deficiency can coexist with B12 or folate deficiency 1
• Do not delay investigation: Investigation should be considered at any level of confirmed iron deficiency, especially with severe degrees 1, 3
• Do not ignore normal ferritin in inflammatory conditions: Use higher cutoff (45 μg/L) and add transferrin saturation 2, 3

Special Considerations for Genetic Causes

If patient fails oral iron and has extreme microcytosis: 1

• ALAS2 defects (X-linked sideroblastic anemia): Trial pyridoxine 50-200 mg daily, continue lifelong at 10-100 mg daily if responsive 1
• IRIDA (TMPRSS6 defects): Requires repeated intravenous iron (iron sucrose or gluconate), rarely achieves complete normalization 1
• SLC25A38 defects: Hematopoietic stem cell transplantation is only curative option 1