Management of Iron Deficiency Anemia in a 17-Year-Old Female
Start oral ferrous sulfate 200 mg once daily on an empty stomach, add vitamin C 500 mg with each dose to enhance absorption, and assess menstrual blood loss as the most likely underlying cause before pursuing invasive gastrointestinal investigations. 1
Immediate Treatment Strategy
Begin oral iron supplementation immediately with ferrous sulfate 200 mg once daily, which is the preferred first-line treatment due to its effectiveness and low cost. 1 Once-daily dosing improves tolerability while maintaining effectiveness compared to multiple daily doses. 1
- Add ascorbic acid (vitamin C) 500 mg with each iron dose to enhance absorption, which is particularly critical given the severely low transferrin saturation of 5%. 2, 1
- Take iron on an empty stomach for optimal absorption, though taking with food is acceptable if gastrointestinal side effects occur. 1
- If ferrous sulfate is not tolerated, switch to ferrous gluconate or ferrous fumarate, which are equally effective alternatives. 2, 1
Expected Response and Monitoring
Hemoglobin should rise by approximately 2 g/dL after 3-4 weeks of treatment. 2, 1 If this response is not achieved, assess for non-adherence, continued blood loss, or malabsorption. 1
- Continue iron therapy for 3 months after anemia correction to fully replenish iron stores, not just until hemoglobin normalizes. 1
- Monitor hemoglobin and red cell indices at 3-month intervals for the first year, then again after another year. 1
Investigation of Underlying Cause
In a 17-year-old female, menstrual blood loss is the most likely cause, occurring in 5-10% of menstruating women. 2 Menorrhagia, pregnancy, and breastfeeding are usually responsible. 2
- Assess menstrual blood loss first using pictorial blood loss assessment charts, which have 80% sensitivity and specificity for detecting menorrhagia. 2, 1
- Screen for celiac disease with antiendomysial antibody and IgA measurement, as this is a common cause of malabsorption in younger patients. 2, 1
- Gastrointestinal endoscopy is NOT routinely indicated in premenopausal women under 45 years without upper GI symptoms. 2, 1
- Only pursue colonic investigation if there are specific indications such as rectal bleeding, family history of colon cancer, or alarm symptoms. 2, 1
When to Consider Intravenous Iron
Switch to IV iron only if specific criteria are met, as parenteral iron is painful, expensive, and carries risk of anaphylactic reactions. 2, 1
Indications for IV iron include:
- Intolerance to at least two different oral iron preparations 1
- Inadequate response to oral iron after 4 weeks despite compliance and absence of acute illness 2, 1
- Conditions affecting iron absorption (celiac disease with ongoing gluten exposure, post-bariatric surgery, inflammatory bowel disease with active inflammation) 1
Note that the rise in hemoglobin is no quicker with parenteral iron than with oral preparations. 2, 1
Critical Pitfalls to Avoid
- Do not prescribe multiple daily doses (e.g., three times daily), as this increases side effects without improving efficacy and stimulates hepcidin elevation that blocks iron absorption for 24 hours. 1, 3
- 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 enhances absorption. 2, 1
- Do not pursue invasive GI investigations (endoscopy, colonoscopy) in young premenopausal women without specific GI symptoms or alarm features. 2, 1
- Do not continue oral iron indefinitely without response - reassess after 4 weeks and switch to IV iron if hemoglobin fails to rise by 1 g/dL. 2, 1
Failure to Respond
If no improvement after 4 weeks despite compliance, assess for continued blood loss and evaluate for malabsorption syndromes. 1