What is the most likely cause of anemia in a 78‑year‑old patient with mild normocytic/macrocytic anemia, low MCHC, high RDW, low transferrin, elevated CRP, and normal vitamin B12, folate, and ferritin, and what is the appropriate management?

Anemia of Chronic Disease with Functional Iron Deficiency

This 78-year-old patient has anemia of chronic disease (ACD) with functional iron deficiency, evidenced by elevated CRP (9.5 mg/L), low transferrin (183 mg/dL), normal-range ferritin (100 ng/mL), and mild normocytic anemia—the most appropriate management is to investigate the underlying inflammatory condition while considering intravenous iron supplementation if the inflammatory source cannot be rapidly corrected. 1

Diagnostic Interpretation

Iron Studies in the Context of Inflammation

• Ferritin 100 ng/mL with elevated CRP indicates anemia of chronic disease rather than absolute iron deficiency, because ferritin is an acute-phase reactant that rises during inflammation and can mask true iron depletion. 1

• Low transferrin (183 mg/dL, normal 200-390) combined with elevated CRP confirms the diagnosis of ACD, as inflammation suppresses transferrin synthesis and increases hepcidin, which blocks iron mobilization from stores. 1

• The combination of ferritin 100 ng/mL with low transferrin suggests functional iron deficiency superimposed on ACD—iron is sequestered in reticuloendothelial cells and cannot be delivered to the bone marrow despite adequate stores. 1

• In inflammatory states, ferritin levels up to 100 µg/L may still reflect iron deficiency; a transferrin saturation calculation (serum iron ÷ TIBC × 100) would provide additional diagnostic clarity, with values <16-20% confirming functional iron deficiency. 1, 2

Hematologic Pattern Analysis

• The mild normocytic anemia (Hgb 10.8 g/dL, MCV 93.3 fL) with low MCHC (29.9 g/dL) and elevated RDW (15.4%) is characteristic of early ACD with evolving functional iron deficiency, as chronic inflammation initially produces normocytic anemia that becomes hypochromic as iron delivery fails. 1

• The reticulocyte count of 2.2% (absolute 86 k/uL) is inappropriately normal for the degree of anemia, indicating inadequate bone marrow response typical of ACD rather than hemolysis or acute blood loss, which would produce reticulocytosis >3%. 1, 3

• Normal vitamin B12 (459 pg/mL) and folate (10.8 ng/mL) exclude megaloblastic causes, ruling out combined nutritional deficiencies that could complicate the picture. 4, 5

Investigation of Underlying Inflammatory Condition

Mandatory Gastrointestinal Evaluation

• All elderly patients with confirmed anemia and elevated inflammatory markers require bidirectional endoscopy (upper endoscopy with duodenal biopsies plus colonoscopy) to exclude gastrointestinal malignancy, as occult GI cancer is the most common serious cause of combined anemia and inflammation in this age group. 1, 2

• Upper endoscopy with duodenal biopsies screens for celiac disease (present in 2-3% of anemia cases), gastric cancer, peptic ulcer disease, and NSAID-induced gastropathy—all of which can produce chronic inflammation and blood loss. 1, 2

• Colonoscopy detects colonic carcinoma, adenomatous polyps, angiodysplasia, and inflammatory bowel disease, which are high-yield findings in patients over 75 years with unexplained anemia and elevated CRP. 1, 2

Additional Inflammatory Workup

• Chronic kidney disease (CKD) should be assessed with serum creatinine and estimated GFR, as CKD produces normocytic anemia through reduced erythropoietin production and contributes to functional iron deficiency. 1, 3, 6

• Chronic heart failure evaluation is warranted if clinical signs are present (dyspnea, edema, elevated BNP), because CHF causes anemia through chronic inflammation, hemodilution, and impaired iron mobilization. 1

• Inflammatory bowel disease, rheumatologic conditions, and chronic infections should be considered based on clinical history, as these are common causes of persistent CRP elevation with functional iron deficiency. 1

Management Algorithm

Iron Supplementation Strategy

• Oral iron supplementation (ferrous sulfate 200 mg three times daily) is unlikely to be effective in ACD with elevated hepcidin, as hepcidin blocks duodenal iron absorption and iron release from macrophages, preventing oral iron from reaching the bone marrow. 1, 2

• Intravenous iron (iron sucrose or ferric carboxymaltose) should be considered if the inflammatory condition cannot be rapidly corrected, as IV iron bypasses hepcidin-mediated blockade and can raise hemoglobin by ≥2 g/dL within 4 weeks even in the presence of inflammation. 1, 2

• A trial of weekly IV iron (50-125 mg) for 8-10 doses can distinguish functional iron deficiency from pure inflammatory block—if hemoglobin rises, functional iron deficiency was present; if no response occurs, inflammation alone is responsible and further iron should be withheld until inflammation resolves. 1

• Monitor serum ferritin during IV iron therapy and do not exceed 500 µg/L, as higher levels indicate iron overload risk without additional therapeutic benefit. 1, 2

Treatment of Underlying Condition

• Definitive management requires treating the underlying inflammatory disorder—resolution of inflammation will normalize hepcidin, restore iron mobilization, and allow endogenous erythropoiesis to recover. 1, 3

• **If chronic kidney disease is present (GFR <60 mL/min/1.73 m²), erythropoiesis-stimulating agents (ESAs) may be indicated once hemoglobin falls below 10 g/dL**, but ESAs should not be initiated until iron deficiency is corrected and transferrin saturation is >20%. 1, 3

• Blood transfusion is reserved for symptomatic patients with hemoglobin <8 g/dL or those with cardiovascular instability, as transfusion carries risks of iron overload, transfusion reactions, and viral transmission in elderly patients. 3, 6, 7

Critical Diagnostic Pitfalls

• Do not attribute anemia in the elderly to "normal aging"—a cause is identifiable in approximately 80% of cases, and failure to investigate can miss treatable malignancy or serious inflammatory disease. 6, 5, 7

• Do not rely on ferritin alone when CRP is elevated—ferritin >100 µg/L in the setting of inflammation does not exclude functional iron deficiency, and transferrin saturation or a trial of IV iron is required for accurate diagnosis. 1

• Do not assume all normocytic anemia is ACD—early iron deficiency, myelodysplastic syndrome, and combined deficiencies can present with normal MCV, and elevated RDW (15.4%) suggests evolving microcytosis or mixed pathology. 1, 2, 6

• Do not overlook gastrointestinal malignancy as the source of chronic inflammation—occult GI cancer produces both blood loss and inflammatory cytokines (IL-6), creating the exact laboratory pattern seen in this patient. 1, 2, 8

• Do not start oral iron empirically without investigating the cause of anemia—in elderly patients with elevated inflammatory markers, the priority is identifying and treating the underlying condition, not empiric iron supplementation. 1, 2, 6