Management of Iron Deficiency Anemia
All patients with IDA require both iron replacement therapy to correct anemia and replenish stores, AND investigation of the underlying cause to prevent recurrence. 1
Iron Replacement Therapy
First-Line Oral Iron
- Ferrous sulfate 200 mg three times daily is the standard treatment (equivalent to 65 mg elemental iron per dose) 1, 2
- Alternative oral formulations include ferrous gluconate and ferrous fumarate, which are equally effective 1
- Liquid preparations may be better tolerated when tablets cause side effects 1
- Adding ascorbic acid (vitamin C) enhances iron absorption and should be considered when response is poor 1
- Continue iron supplementation for 3 months after hemoglobin normalizes to replenish body stores 1
- Expected response: hemoglobin should rise by ≥10 g/L within 2 weeks, or 2 g/dL after 3-4 weeks 1
When to Use Intravenous Iron
Parenteral iron should be used when: 1, 3
- Intolerance to at least two oral iron preparations
- Non-compliance with oral therapy
- Malabsorption conditions (inflammatory bowel disease, celiac disease, post-gastrectomy)
- Ongoing iron losses exceeding absorptive capacity
- Rapid iron repletion is required
Important caveat: IV iron does not produce faster hemoglobin rise than oral iron, but is more effective in specific populations 1, 3
Investigation of Underlying Cause
Men and Postmenopausal Women
All patients require bidirectional GI endoscopy (gastroscopy AND colonoscopy) unless an obvious cause is identified 1
Initial workup must include: 1
- Upper GI endoscopy with small bowel biopsy (to detect celiac disease, gastric pathology)
- Colonoscopy or barium enema (to exclude colorectal cancer)
- Urinalysis or urine microscopy (to exclude urinary tract bleeding)
- Serological screening for celiac disease (found in 3-5% of IDA cases)
Common pitfall: Approximately one-third of men and postmenopausal women with IDA have underlying GI pathology, most commonly malignancy 1, 4
Premenopausal Women
- Women >45 years should be investigated according to the same protocol as men 1
- Women <45 years: Only investigate with upper endoscopy if upper GI symptoms present; otherwise screen for celiac disease with antiendomysial antibodies (plus IgA level to exclude IgA deficiency) 1
- Colonoscopy only if specific indications exist in women <45 years 1
- Menstrual blood loss is the most common cause, but do not assume this without excluding other pathology in appropriate age groups 1, 4
Refractory or Recurrent IDA
Wireless capsule endoscopy should be performed to assess the small bowel when: 1
- IDA is transfusion-dependent
- IDA recurs despite treatment
- Visible blood loss (melena) with negative bidirectional endoscopy
Additional considerations: 1
- Small bowel enteroscopy may detect and treat angiodysplasia in transfusion-dependent cases
- Small bowel radiology only if Crohn's disease suspected
- Faecal occult blood testing has no diagnostic value (insensitive and non-specific)
Monitoring and Follow-Up
After achieving normal hemoglobin: 1
- Monitor hemoglobin and MCV every 3 months for 1 year
- Recheck after an additional year
- Give additional oral iron if hemoglobin or MCV falls below normal
- Further investigation only needed if hemoglobin cannot be maintained with supplementation
Failure to respond to oral iron indicates: 1
- Poor compliance (most common)
- Misdiagnosis
- Continued blood loss
- Malabsorption
Blood Transfusion
Red cell transfusion should only be used for severe, symptomatic IDA with hemodynamic instability 3
Key Clinical Pearls
- Multiple causes may coexist—finding one cause should not stop further investigation 4
- A good response to iron therapy strongly suggests absolute iron deficiency even with equivocal iron studies 1
- Serum ferritin is the single most useful marker, but may be falsely normal in inflammatory conditions 1, 4
- NSAID use is a common contributing factor that must be addressed 1, 4
- Target for audit: 90% of patients should have both upper endoscopy with small bowel biopsy AND colonoscopy/barium enema 1