What is the diagnosis and treatment for a patient with microcytic anemia, given an MCV of 72.1, MCH of 21.4, MCHC of 29.6, and RDW of 18.7?

Diagnosis and Management of Microcytic Anemia with MCV 72.1, MCH 21.4, MCHC 29.6, RDW 18.7

The laboratory values indicate iron deficiency anemia as the most likely diagnosis, which should be treated with oral iron supplementation while investigating the underlying cause of iron loss. 1

Diagnostic Interpretation

• The presented values show a microcytic (MCV <80 fL), hypochromic (MCHC <30 g/dL) anemia with an elevated red cell distribution width (RDW >15%), which is highly characteristic of iron deficiency anemia 1, 2
• An elevated RDW (18.7) with microcytosis strongly suggests iron deficiency, as it reflects the increased variability in red cell size that occurs during iron-deficient erythropoiesis 1
• The combination of low MCV (72.1) and low MCHC (29.6) creates the hypochromic, microcytic picture classic for iron deficiency anemia 2

Recommended Initial Testing

• Serum ferritin measurement is the first recommended laboratory test to confirm iron deficiency anemia 1
• Additional iron studies should include serum iron, total iron-binding capacity (TIBC), and transferrin saturation to complete the diagnostic picture 3
• Peripheral blood smear examination should be performed to assess red cell morphology and confirm the presence of hypochromic, microcytic cells 3

Differential Diagnosis

• Iron deficiency anemia: Most likely given the laboratory values, especially the elevated RDW 1
• Thalassemia trait: Usually presents with microcytosis but with normal or only slightly elevated RDW (typically <18) 1, 2
• Anemia of chronic disease: Can present with microcytosis but typically has normal/high ferritin with low serum iron 3
• Sideroblastic anemia: Consider if iron studies show iron overload rather than deficiency 4
• Lead toxicity: A rare cause of microcytic anemia that should be considered in specific exposure scenarios 5

Management Approach

• For confirmed iron deficiency anemia:

  • Begin oral iron supplementation with ferrous sulfate 325 mg (65 mg elemental iron) 1-3 times daily 3
  • Continue treatment for 3-6 months to replenish iron stores even after hemoglobin normalizes 6
  • Monitor response with repeat CBC after 4-8 weeks of therapy 4

• If oral iron is ineffective or poorly tolerated:

  • Consider intravenous iron formulations 6
  • Evaluate for malabsorption, ongoing blood loss, or incorrect diagnosis 3

Investigation of Underlying Cause

• In adults, iron deficiency anemia is presumed to be caused by blood loss until proven otherwise 1
• Gastrointestinal evaluation is warranted in all adult men and non-menstruating women with iron deficiency anemia 1
• For menstruating women, heavy menstrual bleeding should be assessed as a potential cause 2
• Consider other sources of blood loss or malabsorption (celiac disease, H. pylori infection) 6

Special Considerations

• If iron studies do not confirm iron deficiency, consider hemoglobin electrophoresis to evaluate for thalassemia 3
• For patients with suspected genetic disorders of iron metabolism (if iron studies are inconsistent with simple iron deficiency):
  • Consider bone marrow examination to look for ring sideroblasts 4
  • Genetic testing may be necessary for definitive diagnosis of rare inherited disorders 4

Follow-up

• Monitor hemoglobin and reticulocyte count to assess response to iron therapy 4
• If no response to appropriate iron therapy within 4-8 weeks, reevaluate the diagnosis 3
• Once anemia resolves, continue iron supplementation for 3-6 months to replenish iron stores 6