Iron Deficiency Anemia in Males: Hematology Consultation Guide
All men with confirmed iron deficiency anemia require urgent bidirectional gastrointestinal endoscopy (both upper endoscopy and colonoscopy) to exclude gastrointestinal malignancy, as GI blood loss is the most common cause and asymptomatic gastric and colonic cancers frequently present this way. 1
Pre-Referral Workup Required
Before consulting hematology, the following must be completed:
- Confirm iron deficiency: Serum ferritin <12 μg/dL is diagnostic; ferritin >100 μg/dL essentially excludes iron deficiency 1
- Celiac disease screening: Tissue transglutaminase antibody (IgA) with total IgA level, as celiac disease accounts for 3-5% of all IDA cases 1, 2
- Urinalysis or urine microscopy: To exclude urinary tract bleeding as an alternative source 1, 2
- Complete medication history: Document all NSAID use (including over-the-counter ibuprofen, naproxen, aspirin), anticoagulants, and antiplatelet agents 1, 2
What to Communicate to Hematology
Provide the following information in your consultation:
- Complete blood count with indices: Hemoglobin, MCV, MCH, and red cell distribution width 2
- Iron studies: Ferritin, transferrin saturation, and TIBC 2
- Celiac serology results 2
- Detailed medication list emphasizing NSAIDs and anticoagulants 2
- GI symptoms status: Specifically document presence or absence of abdominal pain, weight loss, change in bowel habits, and dyspepsia 2
- Urinalysis results 2
Expected Gastroenterology Evaluation (Not Hematology)
Critical distinction: Iron deficiency anemia in men is primarily a gastroenterology problem, not a hematology problem. The hematology consultation should facilitate gastroenterology referral for:
- Upper endoscopy with duodenal biopsies: To evaluate for gastric cancer, peptic ulcer disease, angiodysplasia, and celiac disease (even if serology is negative) 1, 2
- Colonoscopy: To exclude colorectal cancer and polyps, which are the most common causes of occult GI blood loss in men 2, 3
- Bidirectional endoscopy in same session: Dual pathology (lesions in both upper and lower GI tract) occurs in 10-15% of patients 1, 4
When to Investigate Small Bowel
Only pursue small bowel investigation if:
- Bidirectional endoscopy is negative AND
- Patient has inadequate response to iron replacement therapy (Hb rise <10 g/L within 2 weeks) OR recurrent IDA 1
Preferred test: Capsule endoscopy is the first-line investigation for small bowel evaluation, as it is highly sensitive for mucosal lesions 1
Iron Replacement Therapy
Start immediately—do not defer while awaiting investigations (unless colonoscopy is imminent, as iron may obscure visualization) 1
Initial treatment regimen:
- Ferrous sulfate 324 mg (65 mg elemental iron) once daily 1, 5
- If not tolerated: reduce to one tablet every other day 1
- Alternative oral preparations or parenteral iron if oral route fails 1
Monitoring protocol:
- Check hemoglobin response at 4 weeks 1
- Continue treatment for approximately 3 months after hemoglobin normalization to replenish iron stores 1
- A hemoglobin rise ≥10 g/L within 2 weeks strongly confirms absolute iron deficiency, even if iron studies were equivocal 1
Common Pitfalls to Avoid
Do not stop investigating after finding one minor lesion: Esophagitis, erosions, aphthous ulceration, or peptic ulcer should not be accepted as the sole cause without completing lower GI investigation, as dual pathology is common 1
Do not assume dietary deficiency is the cause: Even with a positive dietary history, full GI investigation is still required in men 1
Do not skip celiac screening: This treatable cause is easily missed and accounts for 2-5% of cases 1, 6
Do not overlook NSAID use: Patients often fail to report over-the-counter NSAIDs, which are a common cause of occult GI blood loss 6
Long-Term Management
If no cause is identified after complete evaluation: