Treatment Recommendation for Microcytic Anemia with Borderline-Low Ferritin
Start oral ferrous sulfate 200 mg three times daily for at least three months after hemoglobin correction, as this patient has iron deficiency anemia confirmed by the combination of microcytosis (MCV 74.7), elevated RDW (14.3), and ferritin of 38 μg/L. 1
Diagnostic Interpretation
Your patient's laboratory values clearly indicate iron deficiency anemia:
Ferritin of 38 μg/L falls below the optimal diagnostic threshold of 45 μg/L recommended for iron deficiency, and is well below the 100 μg/L level that would suggest anemia of chronic disease 1, 2
The elevated RDW of 14.3% combined with low MCV strongly distinguishes iron deficiency from thalassemia trait, which typically presents with RDW ≤14.0% 1, 2
The hemoglobin A2 of 2.1% is normal (elevated A2 >3.5% would suggest beta-thalassemia trait), effectively ruling out thalassemia as the primary diagnosis 2
Serum ferritin is the single most powerful test for differentiating causes of microcytic anemia, with levels <30 μg/L indicating low body iron stores and levels <45 μg/L providing optimal sensitivity and specificity in practice 1, 2
Treatment Protocol
Oral iron supplementation is first-line therapy:
Prescribe ferrous sulfate 200 mg (containing 65 mg elemental iron) three times daily 1, 3
Continue treatment for at least three months after hemoglobin correction to replenish iron stores, not just until anemia resolves 1, 4
Add ascorbic acid (vitamin C) to enhance iron absorption if tolerated 1, 4
Alternative formulations include ferrous gluconate or ferrous fumarate if ferrous sulfate causes intolerable gastrointestinal side effects 1
Expected Response and Monitoring
A good response confirms the diagnosis:
Hemoglobin should rise ≥10 g/L within 2 weeks if iron deficiency is the cause 1
Monitor hemoglobin and red cell indices at three-month intervals for one year, then annually 1, 4
Provide additional oral iron if hemoglobin or MCV falls below normal during follow-up 1
Critical Investigation Required
You must investigate the underlying source of iron loss:
In men and post-menopausal women, gastrointestinal blood loss is the most common cause and gastrointestinal malignancy must be excluded 4
In premenopausal women, heavy menstrual bleeding is the most common cause, but gastrointestinal sources should still be considered with this degree of iron deficiency 1
Fast-track gastrointestinal referral is warranted for men with Hb <110 g/L or non-menstruating women with Hb <100 g/L 1
When to Consider Alternative Approaches
Switch to intravenous iron if:
Patient fails to respond to oral therapy within 2-4 weeks (consider non-compliance, ongoing blood loss, or malabsorption) 1, 4
Malabsorption is documented (expect hemoglobin increase of at least 2 g/dL within 4 weeks of IV iron) 1, 4
Iron losses exceed oral replacement capacity 4
Refer to hematology if:
Refractory microcytic anemia persists despite adequate iron supplementation for 3 months 4
Very low transferrin saturation with low-normal ferritin (>20 μg/L) suggests IRIDA (iron-refractory iron deficiency anemia), though this is rare 2
Common Pitfalls to Avoid
Do not assume all microcytic anemia is iron deficiency: While your patient clearly has iron deficiency, always confirm with ferritin before starting therapy 1
Do not stop iron therapy when hemoglobin normalizes: Iron stores must be replenished, requiring at least 3 additional months of treatment 1, 4
Do not overlook combined deficiencies: Check B12 and folate if response to iron is suboptimal 1
Do not fail to investigate the source of iron loss: This is mandatory in all adults with confirmed iron deficiency anemia 1, 4