Management of Iron Deficiency Anemia
Start oral ferrous sulfate 200 mg once daily (or alternate-day dosing if better tolerated) with vitamin C 500 mg to enhance absorption, continue for 3 months after hemoglobin normalizes, and escalate to intravenous iron only if oral therapy fails or specific indications exist. 1, 2
Initial Oral Iron Therapy
- Ferrous sulfate 200 mg once daily is the preferred first-line regimen, as it is simple, effective, and inexpensive 1, 2
- Each 324 mg tablet of ferrous sulfate contains 65 mg of elemental iron 3
- Add vitamin C 500 mg with each iron dose to improve absorption 2
- Alternate-day dosing may be better tolerated and improves compliance compared to three-times-daily regimens 2
- Alternative formulations include ferrous gluconate or ferrous fumarate if ferrous sulfate is not tolerated 1, 2
Important caveat: The traditional recommendation of ferrous sulfate 200 mg three times daily 1 increases side effects and paradoxically reduces absorption due to hepcidin elevation 2. Once-daily or alternate-day dosing is now preferred for better tolerance and compliance.
Expected Response and Monitoring
- Hemoglobin should rise by approximately 2 g/dL after 3-4 weeks of treatment 1, 2
- Continue oral iron for 3 months after hemoglobin normalizes to adequately replenish iron stores 1, 2
- Monitor hemoglobin and ferritin every 3 months for the first year, then annually 1, 2
- Resolution of anemia should occur in 80% of patients by 6 months 1
Based on your patient's labs: Hemoglobin is 91 g/L (low), ferritin is 12 µg/L (diagnostic of iron deficiency), MCH is 24.9 pg (low), and iron saturation is elevated at 0.57 (likely recent iron intake or inflammation). The low ferritin confirms iron deficiency anemia requiring treatment.
When to Escalate to Intravenous Iron
Reserve IV iron for specific indications only 1, 4:
- Intolerance to at least two different oral iron preparations 1, 2
- Malabsorption conditions (celiac disease, post-bariatric surgery) 1, 4
- Chronic inflammatory conditions where oral iron is insufficient (CKD, heart failure, IBD, cancer) 4
- Ongoing blood loss exceeding absorptive capacity 2, 5
- Second and third trimesters of pregnancy 4
- Ferritin levels fail to improve after adequate trial of oral iron 2
Available IV formulations include iron sucrose, ferric carboxymaltose, and iron dextran, with newer preparations allowing 1-2 infusions rather than multiple sessions 1, 2
Investigation for Underlying Cause
All patients require evaluation for the source of iron deficiency 2:
- For premenopausal women: Screen for celiac disease with antiendomysial antibodies and IgA levels, evaluate for menorrhagia, pregnancy, and breastfeeding 1, 2
- For men and postmenopausal women: Perform upper endoscopy with small bowel biopsy and colonoscopy to exclude gastrointestinal blood loss and malignancy 2, 6
- Consider gastrointestinal investigation in women with GI symptoms, family history of colorectal cancer, or persistent IDA after iron supplementation 1
Your patient's additional findings: WBC is low at 3.5, neutrophils are low at 1.6, and occasional nucleated RBCs are present. These findings warrant further investigation beyond iron deficiency alone, as they may suggest bone marrow involvement or another hematologic process.
Common Pitfalls to Avoid
- Premature discontinuation before iron stores are replenished leads to rapid recurrence 2
- Prescribing excessive daily doses (>200 mg elemental iron) increases side effects without improving efficacy 2
- Failing to investigate for GI pathology in older patients, assuming dietary insufficiency alone 2
- Not recognizing that continued blood loss will prevent response regardless of supplementation 2
- Using parenteral iron as first-line therapy when oral iron would be appropriate leads to unnecessary risks and costs 1
- Discontinuing therapy due to GI side effects without trying alternative formulations or alternate-day dosing 1, 2
Special Considerations for This Patient
Given the low WBC (3.5), neutropenia (1.6), and occasional nucleated RBCs, consider hematology referral to exclude bone marrow pathology, myelodysplastic syndrome, or other causes of cytopenias beyond simple iron deficiency 2. The elevated CK (242 U/L) may reflect muscle symptoms from anemia but should be monitored.
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