What is the appropriate management for a patient with iron deficiency anemia?

Management of Iron Deficiency Anemia

Interpretation of Laboratory Results

Your patient has iron deficiency without anemia - the total iron is low-normal (51 mcg/dL), transferrin saturation is low at 15% (below the diagnostic threshold of 20%), but hemoglobin is presumably normal since this is not frank anemia, and ferritin is adequate at 124 ng/mL. 1, 2

Treatment Recommendation

Start oral iron supplementation with ferrous sulfate 200 mg (containing 65 mg elemental iron) three times daily, and add vitamin C to enhance absorption. 3, 1

Oral Iron Therapy Details

• Ferrous sulfate 200 mg three times daily is the first-line treatment - this is the most cost-effective and simplest approach, though ferrous gluconate and ferrous fumarate are equally effective alternatives. 3, 1

• Add vitamin C (ascorbic acid) to each dose to enhance iron absorption, particularly important given your patient's borderline iron status. 3

• Alternative dosing if side effects occur: Consider alternate-day dosing (ferrous sulfate 325 mg every other day) which may improve tolerability with similar absorption rates. 3, 2

Expected Response and Monitoring

• Hemoglobin should rise by approximately 2 g/dL after 3-4 weeks of treatment - failure to achieve this suggests poor compliance, continued blood loss, malabsorption, or misdiagnosis. 3, 1

• Continue iron therapy for 3 months after correction of anemia to adequately replenish iron stores, not just correct the hemoglobin. 1

• Recheck ferritin levels after the treatment course - if ferritin doesn't improve despite oral therapy, this indicates either non-compliance, ongoing losses, or malabsorption requiring investigation. 3

Investigation for Underlying Cause

All patients with iron deficiency should be investigated for underlying causes, with the approach stratified by age and sex. 3, 1

For Men and Postmenopausal Women

• Perform bidirectional endoscopy (upper endoscopy with small bowel biopsy AND colonoscopy) to evaluate for gastrointestinal blood loss and malabsorption. 3, 1, 4

• Screen for celiac disease with tissue transglutaminase antibody (IgA type) and total IgA level to exclude IgA deficiency which makes the test unreliable. 3, 1, 4

For Premenopausal Women

• If age >45 years: Investigate with bidirectional endoscopy as above. 3

• If age <45 years without upper GI symptoms: Screen for celiac disease with antiendomysial antibody and IgA measurement; reserve endoscopy for those with upper GI symptoms or positive celiac screening. 3, 1

• Assess for menorrhagia as the most common cause in this population - menstrual blood loss accounts for iron deficiency in 38% of reproductive-age women. 2

Additional Investigations if Bidirectional Endoscopy is Negative

• Small bowel investigation is NOT routinely recommended after negative upper and lower endoscopy unless red flags are present. 4

• Red flags requiring capsule endoscopy, CT, or MRI enterography include: involuntary weight loss, persistent abdominal pain, elevated inflammatory markers (CRP), or ongoing transfusion requirements despite oral iron. 4

When to Use Intravenous Iron

Switch to intravenous iron if oral iron fails, is not tolerated, or absorption is impaired. 3, 2

Specific Indications for IV Iron

• Intolerance to at least two different oral iron preparations - gastrointestinal side effects occur in 5-10% of patients. 3, 5

• Ferritin levels fail to improve after adequate trial of oral iron (typically 3-6 months), suggesting malabsorption or ongoing losses exceeding absorption capacity. 3, 4

• Conditions impairing iron absorption: celiac disease, atrophic gastritis, inflammatory bowel disease with active inflammation, post-bariatric surgery (especially procedures disrupting duodenal absorption). 3, 2, 4

• Chronic inflammatory conditions: inflammatory bowel disease with active inflammation, chronic kidney disease, heart failure, or cancer where oral iron absorption is compromised. 3, 2

• Ongoing blood loss exceeding intestinal absorption capacity: such as intestinal angiodysplasia, portal hypertensive gastropathy refractory to oral iron, or gastric antral vascular ectasia. 3, 5

IV Iron Administration

• Prefer formulations requiring 1-2 infusions over those requiring multiple doses for patient convenience and compliance. 3

• True anaphylaxis is very rare - most reactions are complement activation-related pseudo-allergy (infusion reactions) and should be managed accordingly, not as contraindications to future use. 3

Common Pitfalls to Avoid

• Don't rely solely on ferritin in inflammatory conditions - ferritin is an acute phase reactant and may be falsely elevated despite true iron deficiency; transferrin saturation <20% is diagnostic even when ferritin appears normal. 1, 2

• Don't stop iron therapy when hemoglobin normalizes - continue for 3 months after correction to replenish stores, otherwise recurrence is likely. 1

• Don't assume menstruation explains iron deficiency in premenopausal women over age 45 - they require full investigation like postmenopausal women. 3

• Don't use parenteral iron as first-line therapy - it's more expensive, painful (if intramuscular), carries anaphylaxis risk, and doesn't raise hemoglobin faster than oral preparations when oral iron is tolerated and absorbed. 3