Workup for Mild Anemia in a 70-Year-Old Female
Order a complete iron panel (serum ferritin, transferrin saturation, serum iron, and total iron-binding capacity) together with C-reactive protein, vitamin B12, folate, and a reticulocyte count to evaluate this mild anemia. 1, 2
Initial Laboratory Assessment
The patient meets criteria for mild anemia with hemoglobin 11.8 g/dL (threshold <12.0 g/dL for women) and hematocrit 35.2% 1. The normal AST of 11 IU/L effectively excludes liver disease as a contributing cause 3, 4.
Essential Iron Studies
Iron status evaluation is the cornerstone of anemia workup and must include:
- Serum ferritin – Values <30 µg/L confirm depleted iron stores when inflammation is absent and represent the single most reliable marker for iron deficiency 1, 2
- Transferrin saturation – Levels <15-16% support iron deficiency and are less affected by acute inflammation than ferritin, helping differentiate from anemia of chronic disease 1, 2
- C-reactive protein (CRP) – Must be measured concurrently because ferritin rises as an acute-phase reactant; a normal CRP is required to interpret low ferritin accurately 1, 2
Additional Required Tests
- Vitamin B12 and folate levels – Deficiencies cause macrocytic anemia but can coexist with iron deficiency 1, 5
- Reticulocyte count – A low or inappropriately normal reticulocyte response suggests inadequate bone marrow compensation, consistent with iron deficiency or other production defects 1
- Complete blood count with differential – Evaluates mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), and red cell distribution width (RDW) to characterize the anemia 1
Clinical Significance in Older Adults
Even mild anemia at this level carries substantial clinical consequences. Hemoglobin of 11.8 g/dL is associated with increased risk of hospitalization (adjusted hazard ratio 1.32) and mortality (adjusted hazard ratio 1.86) in elderly populations 6. Mobility difficulty prevalence is significantly higher at hemoglobin 12.0 g/dL compared to 13.5 g/dL, even after adjusting for chronic diseases 7.
Common Etiologies in This Age Group
Approximately one-third of anemia in older adults stems from nutritional deficiency (iron, B12, folate), one-third from chronic inflammation or chronic kidney disease, and one-third remains unexplained after initial evaluation 8. Given the patient's age of 70 years, standard anemia definitions may not fully apply, as hemoglobin thresholds can vary in this population 1.
Critical Diagnostic Pitfalls to Avoid
- Do not rely on ferritin alone without CRP – Inflammation falsely elevates ferritin and masks true iron deficiency 2
- Do not assume normal MCV excludes iron deficiency – MCH typically falls before MCV in early deficiency 2
- Do not limit evaluation to CBC alone – Full iron studies are required for proper diagnosis per WHO criteria 2
Investigation for Underlying Cause
If iron deficiency is confirmed, gastrointestinal evaluation is warranted in this age group. Iron deficiency anemia in older adults often results from occult gastrointestinal bleeding, and endoscopy should be considered to evaluate for malignancy 5, 8. In postmenopausal women, menstrual losses are not a factor, making GI sources more likely 2.
Follow-Up Assessment
Re-measure hemoglobin at 4 weeks if empiric iron therapy is initiated. An increase of ≥1 g/dL confirms iron-deficiency anemia and validates continuation of therapy for an additional 3 months to replenish stores 2. If no hematologic response occurs despite documented adherence, consider hemoglobin electrophoresis to exclude thalassemia trait and evaluate for other causes including myelodysplastic syndrome 2, 5, 8.