What is the management for a patient with microcytic anemia and abnormal hemoglobin, MCV, MCH, and MCHC levels?

Management of Microcytic Anemia

The patient's laboratory values indicate microcytic hypochromic anemia, which requires iron studies including serum ferritin, transferrin saturation, and total iron binding capacity (TIBC) for proper diagnosis and management. 1, 2

Diagnostic Approach

• Serum ferritin is the most specific test for iron deficiency, with levels <15 μg/L indicating absent iron stores and <30 μg/L indicating low body iron stores 2
• A ferritin cut-off of 45 μg/L provides optimal sensitivity and specificity for iron deficiency in clinical practice 2
• Transferrin saturation should be evaluated as it is more sensitive for detecting iron deficiency than hemoglobin concentration alone 2
• The patient's RDW of 12.7% with low MCV (93) suggests possible thalassemia minor rather than iron deficiency anemia, as iron deficiency typically presents with RDW >14.0% 3, 2
• A peripheral blood smear should be ordered to assess RBC morphology 1
• Consider hemoglobin electrophoresis to evaluate for thalassemia if iron studies are normal 1

Diagnostic Algorithm

1. First step: Order iron studies including serum ferritin, serum iron, TIBC, and transferrin saturation 1, 3
2. If low ferritin (<45 μg/L), low serum iron, high TIBC, and transferrin saturation <15%: Confirms iron deficiency anemia 1
3. If normal/high ferritin with low serum iron: Consider anemia of chronic disease 1
4. If normal iron studies with microcytic indices: Order hemoglobin electrophoresis to evaluate for thalassemia 1, 2
5. If unexplained microcytic anemia persists: Consider genetic disorders of iron metabolism or heme synthesis 2

Treatment Approach

• For iron deficiency anemia: Oral iron supplementation with ferrous sulfate 324 mg (65 mg elemental iron) 2-3 times daily 4
• Do not crush or chew tablets for optimal absorption 4
• Continue treatment for at least three months after correction of anemia to replenish iron stores 3
• Alternative formulations include ferrous gluconate and ferrous fumarate if ferrous sulfate is not tolerated 3
• Adding ascorbic acid can enhance iron absorption 3
• A good response to iron therapy is defined as a hemoglobin rise ≥10 g/L within 2 weeks, which confirms iron deficiency 3
• For patients who fail to respond to oral iron therapy, consider intravenous iron if there is malabsorption 3
• For thalassemia: Genetic counseling may be appropriate 1
• For sideroblastic anemia: Consider pyridoxine (vitamin B6) supplementation 3

Monitoring and Follow-up

• Monitor hemoglobin concentration and red cell indices at three-month intervals for one year and then after a further year 3
• Provide additional oral iron if hemoglobin or MCV falls below normal 2
• Expect an increase in hemoglobin of at least 2 g/dL within 4 weeks of starting treatment 3
• For patients receiving iron therapy, monitor for iron overload, particularly in genetic disorders 2

Common Pitfalls and Caveats

• Failure to identify the underlying cause of iron deficiency can lead to recurrent anemia 5, 6
• In men and post-menopausal women, iron deficiency anemia is most commonly caused by gastrointestinal blood loss or malabsorption 2
• Overlooking combined deficiencies, such as iron deficiency coexisting with B12 or folate deficiency 2
• Misdiagnosing thalassemia as iron deficiency can lead to unnecessary iron therapy 6
• Sideroblastic anemia may present with dimorphic RBCs in peripheral blood and requires different management 7