Treatment of Iron Deficiency Anemia

Start with oral ferrous sulfate 200 mg once daily, which is the preferred first-line treatment due to its proven effectiveness and low cost. 1

Initial Oral Iron Therapy

Ferrous sulfate 200 mg once daily is the gold standard treatment for iron deficiency anemia, recommended over multiple daily dosing to improve tolerability while maintaining effectiveness 1, 2
Each 324 mg tablet of ferrous sulfate contains 65 mg of elemental iron 3
Take on an empty stomach for optimal absorption, though taking with food is acceptable if gastrointestinal side effects occur 1
Add vitamin C (ascorbic acid) 500 mg with each iron dose to enhance absorption, particularly when response is suboptimal 4, 1
Alternative oral formulations (ferrous gluconate or ferrous fumarate) are equally effective if ferrous sulfate is not tolerated 4, 1

Hemoglobin should rise by approximately 2 g/dL after 3-4 weeks of treatment 1
If no response occurs within 4 weeks, assess for non-adherence, malabsorption, or ongoing blood loss 1
Continue oral iron therapy for 3 months after anemia correction to fully replenish iron stores 4, 1
Monitor hemoglobin and red cell indices every 3 months for the first year, then again after another year 4, 1

Switch to IV iron if the patient meets any of these specific criteria:

Intolerance to at least two different oral iron preparations 1
Inadequate response to oral iron after 4 weeks of appropriate therapy 1
Inflammatory bowel disease with active inflammation, especially if hemoglobin <10 g/dL 1
Post-bariatric surgery with disrupted duodenal iron absorption 1
Celiac disease with inadequate response despite gluten-free diet adherence 1
Ongoing gastrointestinal blood loss exceeding oral replacement capacity 1
Transfusion-dependent iron deficiency anemia 4

Prefer IV iron formulations that can replace iron deficits with 1-2 infusions 1
Iron dextran can be given as total dose infusion but carries higher anaphylaxis risk 1
Always administer in medical facilities with trained healthcare providers to manage potential hypersensitivity reactions 2
Monitor phosphate levels, as IV iron (especially ferric carboxymaltose) increases hypophosphatemia risk 2

While supplementing iron, simultaneously investigate and treat the underlying cause:

In premenopausal women, assess menstrual blood loss (menorrhagia is responsible in most cases) 4
In men and postmenopausal women, perform upper endoscopy and colonoscopy to evaluate for gastrointestinal bleeding 1
Screen for celiac disease with antiendomysial antibody and IgA measurement 1
Consider atrophic gastritis, chronic inflammation, or bariatric surgery as causes of malabsorption 5
In inflammatory bowel disease, treat active inflammation first to enhance iron absorption 1

Do not prescribe multiple daily doses - once-daily dosing is better tolerated with similar efficacy 1
Do not stop iron therapy when hemoglobin normalizes - continue for 3 months to replenish stores 4, 1
Do not continue oral iron indefinitely without response - reassess after 4 weeks and switch to IV iron if hemoglobin fails to rise 1
Do not overlook vitamin C supplementation when oral iron response is suboptimal 4, 1
Do not fail to identify and treat the underlying cause while supplementing 1

If anemia does not resolve within 6 months despite appropriate iron therapy:

Reassess for ongoing blood loss 1
Evaluate for malabsorption syndromes 1
Consider further gastrointestinal investigation, including small bowel evaluation if transfusion-dependent 4
Verify patient adherence to therapy 1
Consider hematology consultation for complex cases 1

Pregnant women: Start with oral low-dose (30 mg/day) iron at first prenatal visit; increase to 60-120 mg/day for anemia treatment; refer if hemoglobin <9.0 g/dL 1
Inflammatory bowel disease with Hb <10 g/dL: Use IV iron as first-line treatment 1
Post-bariatric surgery: Prefer IV iron due to disrupted duodenal absorption 1