How should I evaluate and manage a 73-year-old patient with mild anemia (hemoglobin 11.3 g/dL)?

Evaluation and Management of Mild Anemia in a 73-Year-Old

In a 73-year-old patient with hemoglobin 11.3 g/dL, you should initiate a diagnostic workup to identify the underlying cause, as this represents true anemia requiring investigation regardless of age, and the etiology is often multifactorial in older adults.

Initial Diagnostic Approach

Confirm Anemia and Classify by MCV

• Hemoglobin 11.3 g/dL meets diagnostic criteria for anemia in this patient, as the threshold is <13.0 g/dL in men and <12.0 g/dL in women 1
• Obtain a complete blood count with mean corpuscular volume (MCV) to classify the anemia as microcytic, normocytic, or macrocytic, as this guides the differential diagnosis 2, 3
• Order a reticulocyte count to assess bone marrow response and distinguish between decreased production versus increased destruction/loss 4, 2
• Review peripheral blood smear for red blood cell morphology abnormalities 4

Essential Laboratory Workup

Iron studies are the highest priority initial tests:

• Serum ferritin, transferrin saturation, serum iron, and total iron-binding capacity to evaluate for iron deficiency 4, 1
• Use ferritin <45 μg/L as the threshold for iron deficiency in anemic patients 1
• In patients with inflammatory conditions, iron deficiency may exist with ferritin 45-100 μg/L; confirmatory testing with transferrin saturation or soluble transferrin receptor may be needed 1

Additional essential tests:

• Vitamin B12 and folate levels to exclude nutritional deficiencies 4, 5
• Renal function (creatinine, eGFR) as chronic kidney disease is a common cause in elderly patients 4, 1
• C-reactive protein to assess for chronic inflammatory conditions 4
• Thyroid function tests, as thyroid disease can cause macrocytic anemia 2

Age-Specific Considerations

Anemia in elderly patients (>70 years) has distinct characteristics:

• Affects >20% of those over 85 years and is often multifactorial 1
• Approximately one-third is due to nutritional deficiency (iron, B12, folate) 5
• Another third is anemia of chronic disease 5
• The remaining third is "unexplained anemia," possibly due to bone marrow resistance to erythropoietin and subclinical inflammation 5
• Multiple contributing causes are common, including poor diet, reduced absorption, occult blood loss, medications (especially aspirin/anticoagulants), and chronic diseases 1

Gastrointestinal Evaluation

If iron deficiency is confirmed, gastrointestinal investigation is mandatory:

• Bidirectional endoscopy (upper endoscopy and colonoscopy) is recommended for iron deficiency anemia in older adults 6, 4
• Upper endoscopy with duodenal biopsies should evaluate for celiac disease, peptic ulcer disease, gastric cancer, and angioectasias 6, 4
• Colonoscopy evaluates for colorectal cancer and other colonic lesions 4
• Obtain tissue transglutaminase IgA with total IgA before endoscopy to screen for celiac disease, though negative serology does not exclude the diagnosis 6

Consider the risk-benefit ratio carefully:

• In elderly patients with major comorbidities, limited performance status, or reduced life expectancy, weigh the risks of invasive procedures against potential benefits 1
• CT colonography may be a more appropriate alternative to colonoscopy in some frail older individuals 1

Common Pitfalls to Avoid

• Do not assume anemia is "normal for age" - while hemoglobin may decline slightly with aging, anemia always warrants investigation as it contributes to worsening physical performance, cognitive function, and frailty 1
• Do not delay investigation for a trial of iron therapy in patients with concerning symptoms 6
• Recognize that chronic kidney disease (GFR <60 mL/min/1.73 m²) is a potential cause, especially when GFR <30 mL/min/1.73 m² 1
• If bidirectional endoscopy is unrevealing, consider small bowel imaging with capsule endoscopy or MR enterography to evaluate for small bowel pathology 6, 4

Iron Repletion Strategy

Once iron deficiency is confirmed:

• Initiate oral iron supplementation first (ferrous sulfate, ferrous fumarate, or ferrous gluconate are reasonable first choices) 1
• Oral iron is absorbed better on an empty stomach, though some patients tolerate it better with meals 1
• Taking iron with 500 mg vitamin C improves absorption 1
• Consider intravenous iron if oral iron is not tolerated, not absorbed, or in severe deficiency 1