What is the interpretation of lab results showing normocytic anemia, and what are the next steps for management?

Normocytic Anemia with Functional Iron Deficiency

This elderly nursing home patient has normocytic anemia (Hgb 9.1 g/dL, MCV 91.3 fL) with functional iron deficiency despite normal ferritin, requiring iron supplementation and evaluation for underlying chronic disease or occult blood loss.

Laboratory Interpretation

Anemia Profile

• Hemoglobin 9.1 g/dL represents moderate anemia (WHO defines anemia as <12 g/dL in women, <13 g/dL in men), with normocytic indices (MCV 91.3 fL, MCH 29.4, MCHC 32.2) 1
• The RBC count of 3.10 million/μL is proportionally reduced, and the normal RDW of 12.9% suggests a single uniform process rather than mixed deficiencies 2

Iron Studies - Critical Finding

• Ferritin 238.5 μg/L with transferrin saturation 28.49% and low TIBC 218 indicates functional iron deficiency in the setting of inflammation 2
• In inflammatory conditions (common in elderly nursing home patients), ferritin between 30-100 μg/L suggests combined iron deficiency and anemia of chronic disease, but ferritin >100 μg/L with transferrin saturation <20% indicates pure anemia of chronic disease 2
• However, this patient's transferrin saturation of 28.49% falls above the 20% threshold but below optimal levels (>30%), representing a gray zone where iron is still functionally deficient despite elevated ferritin 2

Other Findings

• Normal B12 (515) excludes megaloblastic causes 1
• Normal WBC differential with mild eosinophilia (4.8%) is nonspecific 1
• Normal platelet count excludes bone marrow failure syndromes 3

Diagnostic Algorithm

Immediate Next Steps

1. Obtain reticulocyte count - This is the single most important missing test to differentiate production failure (anemia of chronic disease, nutritional deficiency) from destruction/loss (hemolysis, bleeding) 1, 3

   • Low/normal reticulocyte count (<2%) confirms hypoproliferative anemia 1
   • Elevated reticulocyte count (>2%) suggests occult bleeding or hemolysis 4

2. Check inflammatory markers (CRP, ESR) to quantify the degree of chronic inflammation driving the anemia 1

3. Assess for occult blood loss - Stool guaiac testing is essential in elderly patients, as GI bleeding is extremely common and may be chronic/occult 3

4. Review medication list for drugs causing anemia (NSAIDs causing GI bleeding, anticoagulants, bone marrow suppressants) 1

Secondary Evaluation Based on Reticulocyte Count

If reticulocyte count is low/normal:

• Evaluate for chronic kidney disease (check creatinine, eGFR) - a leading cause of normocytic anemia in elderly patients 3, 5
• Screen for hypothyroidism (TSH) as thyroid disorders impair erythropoiesis 1
• Consider bone marrow examination only if other causes excluded and anemia is progressive or symptomatic, though this rarely changes management in elderly patients 6

If reticulocyte count is elevated:

• Check haptoglobin, LDH, indirect bilirubin, and peripheral smear for hemolysis 4, 3
• Pursue endoscopic evaluation for GI bleeding source 3

Management Approach

Iron Supplementation Decision

Despite ferritin >100 μg/L, this patient warrants a trial of iron supplementation because:

• Transferrin saturation of 28.49% indicates suboptimal iron availability for erythropoiesis 2
• In elderly nursing home patients with chronic inflammation, functional iron deficiency is common even with elevated ferritin 2
• Trial oral iron supplementation (ferrous sulfate 325 mg daily or every other day to improve tolerance) and reassess hemoglobin in 4 weeks 1
• An increase in hemoglobin ≥2 g/dL within 4 weeks confirms iron-responsive anemia 1

Treat Underlying Chronic Disease

• Identify and manage any chronic inflammatory conditions (infections, pressure ulcers, arthritis) common in nursing home residents 7, 5
• Optimize nutrition and protein intake, as malnutrition contributes to anemia of chronic disease 5

Avoid Common Pitfalls

• Do not assume normal ferritin excludes iron deficiency in inflammatory states - ferritin is an acute phase reactant and can be falsely elevated 2
• Do not initiate folate supplementation before excluding B12 deficiency (already excluded here with B12 of 515), as this can precipitate neurological complications 1
• Do not transfuse unless symptomatic (dyspnea, chest pain, severe fatigue) or hemoglobin drops below 7-8 g/dL 3
• Do not perform bone marrow biopsy as first-line testing - it is rarely contributory in normocytic anemia and has poor yield in elderly patients 6

Monitoring

• Recheck CBC in 4 weeks after initiating iron supplementation 1
• If no response to iron trial, proceed with reticulocyte count and expanded workup as outlined above 1, 3
• Monitor for symptoms requiring transfusion (rare at Hgb 9.1 g/dL in stable patients) 3