What labs to order for a 75-year-old male with mild anemia (hemoglobin 11-12 g/dL)?

Laboratory Workup for a 75-Year-Old Male with Mild Anemia (Hemoglobin 11-12 g/dL)

For a 75-year-old male with hemoglobin ranging between 11-12 g/dL, a comprehensive laboratory workup should include complete blood count with indices, iron studies, vitamin B12, folate, renal function tests, inflammatory markers, and screening for occult GI blood loss. 1

Initial Laboratory Evaluation

Essential First-line Tests:

• Complete Blood Count (CBC) with differential and indices
• Peripheral blood smear examination
• Reticulocyte count
• Iron studies:
  • Serum ferritin
  • Transferrin saturation (TSAT)
  • Serum iron
  • Total iron-binding capacity (TIBC)
• Vitamin B12 and folate levels
• Renal function tests (BUN, creatinine, eGFR)
• C-reactive protein (CRP) and/or erythrocyte sedimentation rate (ESR)
• Liver function tests
• Fecal occult blood test

Rationale for Testing

In older adults with anemia, approximately one-third have nutritional deficiency, one-third have anemia of chronic inflammation or chronic kidney disease, and one-third have unexplained anemia 1, 2. This distribution guides our testing approach.

Secondary Evaluation Based on Initial Results

If Iron Deficiency is Suspected:

• Serum ferritin <30 μg/L indicates iron deficiency without inflammation
• Serum ferritin 30-100 μg/L with low transferrin saturation (<20%) may represent combined iron deficiency and anemia of chronic disease 1
• GI evaluation is warranted in men with iron deficiency anemia as GI blood loss is the most common cause 3

If Renal Insufficiency is Identified:

• If eGFR <60 mL/min/1.73 m², anemia may be related to decreased erythropoietin production 3, 1
• Consider erythropoietin level if renal function is impaired

If Initial Tests are Inconclusive:

• Hemolysis workup: LDH, haptoglobin, direct Coombs test
• Consider bone marrow examination if unexplained cytopenias are present
• Screening for chronic diseases: TSH, hemoglobin electrophoresis
• Consider testing for pyruvate kinase deficiency if hemolysis is suspected 3

Special Considerations for Elderly Patients

• Anemia should not be attributed to age alone, despite its higher prevalence in older adults 4
• Even mild anemia (Hb 11-12 g/dL) in elderly males warrants thorough investigation as it may indicate serious underlying disease 3
• Consider plasma volume expansion as a potential contributor to anemia, particularly in patients with heart or liver disease 5

Common Pitfalls to Avoid

1. Misinterpreting ferritin levels: Ferritin is an acute phase reactant and may be falsely elevated in inflammatory states despite iron deficiency 1

2. Overlooking dual pathology: Significant causes of bleeding may exist in both upper and lower GI tracts, especially in older patients 3

3. Incomplete evaluation: Failing to investigate mild anemia can miss early malignancies or other serious conditions 3

4. Dilutional anemia: Failing to consider plasma volume expansion as a cause of anemia, particularly in patients with heart failure or liver disease 5

5. Premature cessation of workup: Stopping investigation after finding one abnormality, when multiple factors may contribute to anemia in elderly patients 1, 2

Follow-up Recommendations

• Repeat CBC in 4-8 weeks to assess response to any initiated treatment
• Continue monitoring hemoglobin levels at least annually, or more frequently if unstable
• If anemia persists despite appropriate treatment, consider referral to a hematologist for further evaluation

This systematic approach ensures thorough evaluation of mild anemia in elderly males, addressing the most common causes while remaining vigilant for serious underlying conditions.