What is the next step in managing a patient with microcytic hypochromic anemia and thrombocytosis?

Management of Microcytic Hypochromic Anemia with Thrombocytosis

The next step in managing a patient with microcytic hypochromic anemia and thrombocytosis should be iron studies, specifically serum ferritin, transferrin saturation, and iron levels to determine if iron deficiency is the cause. 1, 2

Diagnostic Approach

• The CBC shows classic findings of microcytic hypochromic anemia: low hemoglobin (11.0 g/dL), low MCH (25.1 pg), low MCHC (31.0 g/dL), and elevated RDW (15.6%) 1
• The elevated RDW >14.0% with low MCV strongly suggests iron deficiency anemia rather than thalassemia 1
• Thrombocytosis (512 x10³/uL) is a common reactive finding in iron deficiency anemia 3
• 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 1
• Transferrin saturation provides additional diagnostic value and is more sensitive than hemoglobin concentration alone 1

Initial Management Algorithm

1. Order iron studies immediately:

   • Serum ferritin
   • Serum iron
   • Total iron binding capacity (TIBC)
   • Transferrin saturation
   • Consider serum transferrin receptor levels 1, 2

2. If iron deficiency is confirmed (most likely scenario):

   • Begin oral iron supplementation with ferrous sulfate 200 mg three times daily 1
   • Continue treatment for at least three months after anemia correction to replenish iron stores 1
   • Alternative formulations include ferrous gluconate and ferrous fumarate if ferrous sulfate is not tolerated 1, 4

3. Investigate the cause of iron deficiency:

   • For premenopausal women: evaluate menstrual blood loss 3
   • For all patients: evaluate for gastrointestinal blood loss (occult blood testing, consider endoscopy) 5
   • Consider malabsorption disorders 5

Monitoring Response

• Expect a hemoglobin rise ≥10 g/L within 2 weeks of starting iron therapy, which confirms iron deficiency 1
• Monitor hemoglobin concentration and red cell indices at three-month intervals for one year 1
• Monitor platelet count, which should normalize with successful iron therapy 3

Alternative Diagnoses to Consider

• If iron studies are normal or iron stores are elevated, consider:
  • Anemia of chronic disease (check inflammatory markers, kidney function) 3, 2
  • Thalassemia (consider hemoglobin electrophoresis if MCV is disproportionately low compared to hemoglobin level) 1, 6
  • Sideroblastic anemia (rare, consider if iron studies show iron overload) 7, 1

Special Considerations

• For patients who fail to respond to oral iron:
  • Consider intravenous iron if there is malabsorption or intolerance to oral preparations 1, 4
  • Expect hemoglobin increase of at least 2 g/dL within 4 weeks of IV iron administration 1
• For genetic disorders affecting iron metabolism:
  • Consider specialized testing if standard iron therapy fails 7
  • Some rare conditions may require erythropoietin, transfusions, or chelation therapy 7, 1

Pitfalls to Avoid

• Don't assume thalassemia without checking iron studies first, as iron deficiency is much more common 2, 6
• Don't overlook combined deficiencies (e.g., iron deficiency with B12 or folate deficiency) 1
• Don't miss underlying malignancy or inflammatory conditions that may present with both anemia and thrombocytosis 3
• Don't forget to treat long enough to replenish iron stores, not just correct the hemoglobin 1, 5