In an 82‑year‑old man with a progressive hemoglobin decline over six months and iron studies essentially normal with mildly low ferritin and a Mentzer index of 25, does this warrant further investigation?

Progressive Anemia in an 82-Year-Old Male Warrants Urgent Investigation

Yes, this hemoglobin drop from 112 g/L to 82 g/L over 6 months in an 82-year-old male absolutely requires comprehensive investigation, as gastrointestinal malignancy is a priority concern in elderly men with iron deficiency anemia. 1

Why This Requires Investigation

Severity and Rate of Decline

• The current hemoglobin of 82 g/L (8.2 g/dL) falls well below the threshold requiring urgent investigation in men (Hb <12 g/dL), and the progressive decline over 6 months suggests ongoing blood loss 1
• Lower hemoglobin levels correlate with more serious underlying disease, making this particularly concerning 1
• In elderly men without other obvious causes, gastrointestinal blood loss is the most common etiology of iron deficiency anemia 1

Iron Studies Interpretation

• The mildly decreased ferritin combined with the anemia pattern indicates true iron deficiency, not just anemia of chronic disease 1, 2
• In non-dialysis patients not on erythropoietic agents and without menstrual losses, iron deficiency should prompt careful assessment for gastrointestinal bleeding 1
• Ferritin levels <25 ng/mL in males predict insufficient iron stores for effective erythropoiesis 1

Mentzer Index Significance

• A Mentzer index of 25 (MCV/RBC count) strongly suggests iron deficiency anemia rather than thalassemia trait (cutoff typically <13 for thalassemia) 3, 4
• This confirms the anemia is microcytic and related to iron deficiency, not a hemoglobinopathy 3

Required Investigations

Gastrointestinal Evaluation (Priority)

• Both upper and lower GI endoscopy should be performed, as asymptomatic gastric and colonic carcinoma commonly present with iron deficiency anemia in this demographic 1
• Dual pathology (bleeding sources in both upper and lower GI tracts) occurs in 1-10% of patients and increases with age 1
• Upper endoscopy with duodenal biopsies should be performed even if coeliac serology is negative, given the clinical presentation 1

Additional Laboratory Testing

• Coeliac serology (tissue transglutaminase antibody) should be obtained, as coeliac disease has approximately 5% prevalence in iron deficiency anemia patients 1
• Complete iron panel including transferrin saturation (TSAT) to fully characterize iron status 1, 2
• Reticulocyte count to assess bone marrow response 1
• Renal function (creatinine, eGFR) to exclude chronic kidney disease as a contributor 1

Medication Review

• Document use of aspirin and NSAIDs, which are common causes of occult GI bleeding and iron deficiency 1
• These medications should be stopped if possible during the investigation 1

Common Pitfalls to Avoid

• Do not assume age-related decline: Anemia is not a normal consequence of aging and reflects poor health and increased vulnerability to adverse outcomes in older persons 1
• Do not delay investigation based on "mild" ferritin reduction: Even mildly low ferritin in the context of significant anemia warrants full workup 1
• Do not stop at negative coeliac serology: Duodenal biopsies may still reveal pathology including gastric causes of bleeding 1
• Do not miss dual pathology: Elderly patients may have multiple bleeding sources requiring both upper and lower GI evaluation 1

Clinical Context

The combination of advanced age, male sex, progressive anemia, and iron deficiency creates a high pretest probability for serious pathology including malignancy. The rate of hemoglobin decline (30 g/L over 6 months) indicates ongoing blood loss that exceeds the body's compensatory mechanisms. This clinical scenario demands prompt and thorough investigation rather than empiric iron supplementation alone, as treating the anemia without identifying the underlying cause could mask a serious diagnosis and delay potentially curative treatment.