What labs are needed to evaluate chronic anemia?

Laboratory Evaluation for Chronic Low-Grade Anemia in an Elderly Man

A comprehensive laboratory workup for chronic low-grade anemia in an elderly man should include a complete blood count with indices, reticulocyte count, iron studies (ferritin, iron, TIBC, transferrin saturation), vitamin B12, folate, renal function tests, and stool occult blood testing. 1, 2

Initial Laboratory Assessment

First-line Tests

• Complete Blood Count (CBC) with indices
  • Provides information on MCV to classify anemia as microcytic, normocytic, or macrocytic
  • Evaluates presence of other cytopenias (WBC, platelets)
• Reticulocyte count
  • Assesses bone marrow response to anemia
  • Low reticulocyte index indicates decreased production
  • High reticulocyte index suggests blood loss or hemolysis
• Iron studies
  • Serum iron
  • Total iron binding capacity (TIBC)
  • Transferrin saturation (TSAT) - less than 15% suggests iron deficiency
  • Ferritin - less than 30 ng/mL indicates iron deficiency
• Renal function tests
  • BUN, creatinine (anemia may develop with creatinine as low as 2.0 mg/dL)
• Stool guaiac test for occult blood
  • Essential to rule out gastrointestinal bleeding, especially in elderly men

Second-line Tests

• Vitamin B12 and folate levels
  • Particularly important if MCV is elevated (>100 fL)
• Hemolysis panel if indicated
  • Haptoglobin
  • LDH
  • Indirect bilirubin
• Peripheral blood smear review
  • Critical to confirm RBC size, shape, and color

Algorithm Based on MCV Results

If Microcytic (MCV < 80 fL)

1. Check iron studies:
   • Low ferritin, low iron, high TIBC → Iron deficiency anemia
   • Low iron, low TIBC, normal/high ferritin → Anemia of chronic disease
   • Normal iron studies → Consider thalassemia (hemoglobin electrophoresis)

If Normocytic (MCV 80-100 fL)

1. Check reticulocyte count:
   • If low:
     • Check renal function (creatinine ≥ 2.0 mg/dL suggests renal anemia)
     • Check inflammatory markers (CRP, ESR) for anemia of chronic inflammation
     • Consider bone marrow dysfunction
   • If high:
     • Evaluate for blood loss (stool guaiac, endoscopy)
     • Consider hemolysis panel

If Macrocytic (MCV > 100 fL)

1. Check vitamin B12 and folate levels
2. Check liver function tests
3. Review medication list for drugs causing macrocytosis
4. Consider myelodysplastic syndrome, especially in elderly

Special Considerations for Elderly Men

• Gastrointestinal malignancy must be ruled out, particularly with iron deficiency
• Anemia of chronic disease is common in elderly patients with inflammatory conditions
• Multiple etiologies may coexist (e.g., iron deficiency plus renal insufficiency)
• Chronic blood loss from medications (NSAIDs, anticoagulants) should be considered

Common Pitfalls to Avoid

• Failing to check iron studies in all cases of anemia
• Missing occult gastrointestinal bleeding in elderly men with iron deficiency
• Overlooking renal insufficiency as a cause of anemia
• Assuming a single etiology when multiple factors may contribute
• Misinterpreting ferritin levels in the presence of inflammation (ferritin is an acute phase reactant and may be falsely elevated)

Follow-up Testing

Based on initial results, additional specialized testing may be needed:

• Endoscopy (upper and/or lower) if iron deficiency is confirmed
• Bone marrow examination if myelodysplastic syndrome or other bone marrow disorder is suspected
• Hemoglobin electrophoresis if thalassemia is suspected
• Erythropoietin level if renal insufficiency is present

By following this systematic approach to laboratory evaluation, the underlying cause of chronic anemia in an elderly man can be identified, allowing for appropriate treatment to improve quality of life and reduce morbidity and mortality 2.