How should a patient with iron deficiency anemia be treated?

Treatment Approach for Iron Deficiency Anemia

Start oral ferrous sulfate 200 mg once daily immediately, as this is the preferred first-line treatment for iron deficiency anemia with severely low iron saturation (7.75%) and low hemoglobin (8.1 g/dL). 1

Immediate Treatment Strategy

Oral Iron Supplementation

• Take ferrous sulfate 200 mg once daily 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, which is particularly critical given the severely low transferrin saturation of 7.75% 1
• Alternative formulations (ferrous gluconate or ferrous fumarate) are equally effective if ferrous sulfate is not tolerated 1
• Continue oral iron therapy for 3 months after hemoglobin normalizes to fully replenish iron stores 1

Expected Response and Monitoring

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

When to Switch to Intravenous Iron

Consider IV iron if the patient meets any of these criteria:

• Intolerance to at least two different oral iron preparations 1, 2
• Inadequate response to oral iron therapy after 4 weeks 1
• Conditions affecting iron absorption such as inflammatory bowel disease with active inflammation, celiac disease with ongoing gluten exposure, or post-bariatric surgery 1
• Ongoing gastrointestinal blood loss exceeding oral replacement capacity 1
• Hemoglobin below 10 g/dL in patients with inflammatory bowel disease 1

IV Iron Formulations

• Prefer ferric carboxymaltose (500-1000 mg single doses, delivered within 15 minutes) as the preferred IV iron formulation 1
• Avoid iron dextran preparations due to higher risk of anaphylaxis requiring test doses 1

Investigation of Underlying Cause

The severely low iron saturation (7.75%) and low TIBC (237) indicate true iron deficiency requiring investigation:

For Premenopausal Women

• Assess menstrual blood loss first, as menorrhagia, pregnancy, and breastfeeding are responsible for iron deficiency in 5-10% of menstruating women 1
• Consider pictorial blood loss assessment charts, which have 80% sensitivity and specificity for detecting menorrhagia 1
• Screen for celiac disease with antiendomysial antibody and IgA measurement, as this is a common cause of malabsorption 1, 3

For Men and Postmenopausal Women

• Perform bidirectional endoscopy (gastroscopy and colonoscopy) to evaluate for gastrointestinal blood loss, as upper gastrointestinal cancer is 1/7 as common as colon cancer in this population 3
• Screen for celiac disease with antiendomysial antibody and IgA measurement 1, 3

Additional Investigations if Endoscopy is Negative

• Small intestine investigation (capsule endoscopy, CT, or MRI enterography) should be conducted only if there are red flags indicating malignant or inflammatory small bowel disease, such as involuntary weight loss, abdominal pain, or increased CRP 3

Critical Pitfalls to Avoid

• Do not use multiple daily doses of oral iron - 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 1
• Do not overlook vitamin C supplementation when oral iron response is suboptimal, as this significantly reduces absorption 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 fail to identify and treat the underlying cause while supplementing iron 1

Failure to Respond

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

• Reassess for ongoing blood loss 1
• Evaluate for malabsorption syndromes 1, 3
• Consider further gastrointestinal investigation 1
• Verify patient adherence to therapy 1
• Consider hematology consultation for complex cases 1