Treatment of Iron Deficiency Anemia
Oral iron supplementation with ferrous sulfate 325 mg daily (or on alternate days) is the recommended first-line treatment for this patient with clear iron deficiency anemia, given the laboratory values showing ferritin of 16 μg/L, transferrin saturation of 0.09, and iron of 7 μmol/L. 1
Diagnostic Confirmation
Your patient has absolute iron deficiency anemia based on:
- Ferritin <30 μg/L (16 μg/L) - highly specific for iron deficiency 2
- Transferrin saturation <15% (0.09 or 9%) - well below the normal threshold 2
- Low serum iron (7 μmol/L) 2
A ferritin <15 μg/L has 99% specificity for iron deficiency in the absence of inflammation 2. The combination of all three abnormal parameters confirms absolute iron deficiency rather than functional deficiency or anemia of chronic disease 2.
Treatment Algorithm
First-Line: Oral Iron Therapy
Oral iron should be initiated as first-line treatment for patients with iron deficiency whose disease is clinically inactive and who have not previously been intolerant to oral iron 2, 1.
Specific dosing:
- Ferrous sulfate 325 mg daily (containing 65 mg elemental iron) 3
- Alternate-day dosing (325 mg every other day) improves absorption and reduces adverse effects 1, 4
- Continue for at least 3-6 months to replenish iron stores 1
Response monitoring:
- Check hemoglobin in 2-4 weeks 4, 5
- Expect 1-2 g/dL increase in hemoglobin within one month if treatment is effective 5
- If no response, consider malabsorption, ongoing blood loss, or need for intravenous iron 5
When to Use Intravenous Iron Instead
Intravenous iron should be considered as first-line treatment in specific circumstances 2:
- Clinically active inflammatory bowel disease 2
- Previous intolerance to oral iron (occurs in ~50% of patients) 1, 4
- Hemoglobin <100 g/L 2
- Malabsorption conditions (celiac disease, post-bariatric surgery, atrophic gastritis) 1
- Chronic inflammatory conditions (heart failure, chronic kidney disease, inflammatory bowel disease, cancer) 1, 4
- Second or third trimester of pregnancy 1
- Ongoing blood loss 1
IV iron formulations include ferric carboxymaltose, iron sucrose, or iron dextran, with newer formulations having <1% hypersensitivity risk 2, 4.
Critical Next Steps: Identify the Underlying Cause
The cause of iron deficiency must always be investigated except in very specific situations 6. This is essential because serious diseases like gastrointestinal cancer can present with iron deficiency 5.
Initial evaluation should include:
- Detailed menstrual history (if premenopausal woman) - heavy menstrual bleeding is the most common cause in this population 1, 4
- Gastrointestinal symptoms and medication history (NSAIDs, anticoagulants) 1
- Dietary assessment 1
- Serological testing for celiac disease 2, 6, 4
- Testing for Helicobacter pylori infection 4
- Urine analysis to exclude hematuria 6
Endoscopic evaluation:
- Men and postmenopausal women: Bidirectional endoscopy (gastroscopy and colonoscopy) should be performed to exclude gastrointestinal malignancy 4, 5
- Premenopausal women with plausible cause (heavy menstrual bleeding): Reasonable to treat the bleeding source and provide iron supplementation initially, with endoscopy if no response 4, 5
- If initial endoscopy is normal but anemia persists or is severe, consider small bowel evaluation with capsule endoscopy 6
Common Pitfalls to Avoid
- Don't assume dietary deficiency alone - recurrent blood loss accounts for 94% of cases in adults 4
- Don't miss celiac disease - it's a common and treatable cause of iron deficiency 6, 4
- Don't use daily dosing if poorly tolerated - alternate-day dosing improves adherence with similar efficacy 1, 4
- Don't delay investigation in men or postmenopausal women - 9% of patients >65 years with iron deficiency anemia have gastrointestinal cancer 5
- Don't confuse with anemia of chronic disease - in that condition, ferritin is typically >100 μg/L with low transferrin saturation 2