How should I evaluate and manage iron‑deficiency anemia in a 56‑year‑old man with ferritin 12 ng/mL, serum iron 32 µg/dL, total iron‑binding capacity 389 µg/dL, and transferrin saturation 8%?

Severe Absolute Iron Deficiency in a 56-Year-Old Man

This 56-year-old man has severe absolute iron deficiency requiring immediate oral iron supplementation and urgent bidirectional endoscopy to exclude gastrointestinal malignancy.

Diagnostic Confirmation

Your patient's laboratory values definitively confirm severe iron deficiency:

• Ferritin 12 ng/mL is below the diagnostic threshold of <15 ng/mL, which has 99% specificity for absolute iron deficiency 1
• Transferrin saturation 8% (calculated as [32 ÷ 389] × 100) is far below the diagnostic cutoff of <16% used to confirm iron deficiency in adults without inflammation 1, 2
• Elevated TIBC 389 µg/dL reflects the body's compensatory attempt to capture more circulating iron when stores are depleted 1, 2

This constellation—low ferritin, low serum iron, elevated TIBC, and severely reduced transferrin saturation—represents classic absolute iron deficiency requiring both treatment and investigation 1, 3.

Immediate Treatment Protocol

Start Oral Iron Without Delay

• Initiate ferrous sulfate 325 mg (65 mg elemental iron) daily or every other day immediately; do not wait for completion of diagnostic workup 1, 3, 4
• Alternate-day dosing (60–65 mg elemental iron every other day) improves absorption by 30–50% and reduces gastrointestinal side effects compared with daily dosing 1, 3
• Take on an empty stomach for optimal absorption, or with meals if gastrointestinal symptoms (nausea, constipation, diarrhea) occur 1
• Expected response: hemoglobin should rise by ≥10 g/L within 2 weeks of starting therapy 1, 5, 3

When to Switch to Intravenous Iron

Transition to intravenous ferric carboxymaltose (15 mg/kg, maximum 1000 mg per dose) if any of the following occur 1, 6, 4:

• Oral iron intolerance (marked nausea, constipation, or diarrhea)
• Lack of hemoglobin response after 8–10 weeks of adequate oral therapy
• Confirmed malabsorption (celiac disease, inflammatory bowel disease, post-bariatric surgery)
• Ongoing blood loss exceeding oral replacement capacity
• Chronic inflammatory conditions (chronic kidney disease, heart failure, cancer)

Mandatory Gastrointestinal Investigation

Why Endoscopy Is Urgent in This Patient

• In adult men and postmenopausal women, iron deficiency may be the sole manifestation of gastrointestinal malignancy; urgent bidirectional endoscopy (gastroscopy + colonoscopy) is mandatory 1, 7, 3, 4
• Nine percent of patients older than 65 years with iron deficiency anemia have a gastrointestinal cancer when evaluated 5
• Upper GI endoscopy reveals a cause in 30–50% of patients, and dual pathology (both upper and lower GI lesions) occurs in 10–15% of cases 7

Additional Screening Tests

Perform these tests concurrently with endoscopy scheduling 1, 7, 3, 4:

• Tissue transglutaminase IgA antibody (plus total IgA level) to screen for celiac disease, which accounts for 3–5% of iron deficiency cases and can cause treatment failure if missed 1, 7
• Non-invasive Helicobacter pylori testing (stool antigen or urea breath test), as the organism impairs iron absorption 1, 7
• Urinalysis or urine microscopy to exclude renal-tract bleeding 7

Follow-Up and Monitoring

• Repeat complete blood count and ferritin at 8–10 weeks after initiating oral iron to assess response 1, 3
• Target ferritin >100 ng/mL to fully restore iron stores and prevent recurrence 1
• If hemoglobin does not rise by ≥10 g/L within 2 weeks, or if ferritin fails to increase after 8–10 weeks of adequate oral iron, evaluate for ongoing occult bleeding, malabsorption, or need for intravenous iron 1, 5, 3
• Continue oral iron for 3 months after hemoglobin normalizes to achieve target ferritin >100 ng/mL; premature discontinuation leads to rapid recurrence 1

Critical Pitfalls to Avoid

• Do not delay endoscopy based on age or absence of gastrointestinal symptoms; gastrointestinal malignancy can present solely as iron deficiency without other manifestations 1, 7, 3
• Do not assume dietary insufficiency alone explains this degree of iron deficiency in an adult man; recurrent blood loss is responsible for 94% of cases 3
• Do not overlook celiac disease screening; its 3–5% prevalence in iron deficiency cases can lead to treatment failure if not identified 1, 7
• Do not stop iron therapy once hemoglobin normalizes; an additional 3 months of supplementation is required to replenish stores (ferritin >100 ng/mL) 1