What are the Canadian guidelines for treating iron deficiency anemia in adult men?

Canadian Guidelines for Iron Deficiency Anemia in Adult Men

Immediate Diagnostic Confirmation

All adult men with suspected iron deficiency anemia require confirmation of both anemia and iron deficiency before proceeding with investigation. 1

• Define anemia as hemoglobin <13 g/dL (below the lower limit of normal for your laboratory) 1, 2
• Confirm iron deficiency with serum ferritin, which is the single most powerful test for iron deficiency 1
• Serum ferritin <12-45 ng/mL confirms iron deficiency, though values may be falsely elevated in inflammatory conditions 1, 2
• If iron studies are equivocal, a hemoglobin rise ≥10 g/L within 2 weeks of iron therapy strongly suggests absolute iron deficiency 1, 2

Mandatory Pre-Endoscopy Screening

Before gastrointestinal investigation, three screening tests must be completed in all adult men with confirmed iron deficiency anemia: 1, 2

• Celiac disease screening with tissue transglutaminase antibody (IgA type) plus total IgA level, as celiac disease accounts for 3-5% of all iron deficiency anemia cases 1, 3
• Urinalysis or urine microscopy to exclude urinary tract bleeding as an alternative source 1, 2
• Comprehensive medication history explicitly documenting all NSAID use (including over-the-counter ibuprofen, naproxen, aspirin), anticoagulants, and antiplatelet agents 3, 2

Gastrointestinal Investigation Protocol

Upper and lower gastrointestinal investigations should be performed in all adult men with confirmed iron deficiency anemia unless there is a history of significant overt non-gastrointestinal blood loss. 1

First-Line Endoscopic Approach

• Gastroscopy (esophagogastroduodenoscopy) and colonoscopy should be the first-line investigations 1, 2
• Obtain duodenal biopsies during gastroscopy if celiac serology is positive or clinical suspicion remains high 1, 2
• CT colonography is a reasonable alternative to colonoscopy in patients not suitable for colonoscopy 1
• Colonoscopy has advantages over CT colonography but either is acceptable; both are preferable to barium enema 1

Critical Decision Point After Initial Endoscopy

Only the presence of advanced gastric cancer or confirmed celiac disease should deter lower gastrointestinal investigation after gastroscopy. 1

• Even if celiac disease is found, lower gastrointestinal investigation should still be considered in patients aged >50, with marked anemia, or with significant family history of colorectal carcinoma 1
• Multiple etiologies coexist in 10-15% of patients, so finding one cause should not stop the investigation 3

Management of Recurrent or Refractory Cases

Further investigation is warranted only in specific circumstances after negative bidirectional endoscopy: 1

• Hemoglobin cannot be restored or maintained with iron therapy 1
• Symptoms suggestive of small bowel disease are present 1
• Transfusion-dependent anemia develops 1
• Visible blood loss continues 1

Small Bowel Investigation

• Wireless capsule endoscopy plays an important role in assessment of the small bowel for recurrent or refractory iron deficiency anemia 1, 2
• Direct visualization of the small bowel is not necessary unless the above criteria are met 1

Helicobacter Pylori Management

In patients with recurrent iron deficiency anemia and normal gastroscopy and colonoscopy results, Helicobacter pylori should be eradicated if present. 1

Iron Replacement Therapy

Iron replacement therapy should be initiated in combination with investigation to establish the underlying cause. 1

• Oral iron therapy is the standard approach for repleting iron stores 4
• Parenteral therapy may be used in patients who cannot tolerate or absorb oral preparations 4
• A good response to iron therapy (hemoglobin rise ≥10 g/L within 2 weeks) is highly suggestive of absolute iron deficiency even if iron studies are equivocal 1

Critical Pitfalls to Avoid

Common errors in managing iron deficiency anemia in adult men include: 3, 2

• Assuming all anemia must be from gastrointestinal bleeding, which misses treatable malabsorption and nutritional causes 3
• Failing to ask specifically about over-the-counter NSAID use, as patients often don't consider these medications worth mentioning 3, 2
• Not screening for celiac disease, which is found in 3-5% of cases 1, 3
• Stopping investigation after finding one minor cause without completing lower gastrointestinal investigation 3
• Accepting minor findings as the sole cause without full evaluation 3

Long-Term Prognosis

Hemoglobin levels normalize with iron replacement therapy in most cases, but iron deficiency anemia recurs in a minority on long-term follow-up. 1

• Approximately 67% of patients remain anemic despite adequate therapy during long-term follow-up 5
• After appropriate initial gastrointestinal evaluation, new gastrointestinal malignancies are rarely identified in patients with persistent iron deficiency anemia 5
• The long-term outlook is generally good even when no cause is detected 1

Faecal Occult Blood Testing

Faecal occult blood testing is of no benefit in the investigation of iron deficiency anemia and should not be used for risk stratification. 1