What is the next step in managing a patient with potential iron deficiency anemia?

Management of Borderline Iron Deficiency Without Anemia

Start oral iron supplementation immediately with ferrous sulfate 200 mg three times daily (or on alternate days) and screen for celiac disease, while determining if gastrointestinal investigation is warranted based on patient demographics. 1

Interpretation of Laboratory Results

Your patient presents with:

• Normal hemoglobin (13.6 g/dL, within reference range 11.7-15.5)
• Borderline-low ferritin (55 ng/mL, within reference range but approaching lower threshold)
• Normal iron studies (iron 82 mcg/dL, TIBC 406 mcg/dL, saturation 20%)
• Low MCH and MCHC (26.6 pg and 31.7 g/dL respectively)

This represents early iron depletion without frank anemia, though the slightly elevated RBC count (5.12 million/uL) with low MCH/MCHC suggests compensatory erythropoiesis. 1

Immediate Management Steps

1. Iron Supplementation

All patients with iron deficiency should receive iron supplementation to correct deficiency and replenish body stores, even without anemia. 1

• First-line: Ferrous sulfate 200 mg three times daily, OR alternate-day dosing (equally effective with better tolerance) 1, 2
• Alternative formulations: Ferrous gluconate or ferrous fumarate if sulfate not tolerated 1
• Continue for 3 months after correction to replenish iron stores 1
• Consider adding ascorbic acid if response is poor (enhances absorption) 1

2. Celiac Disease Screening

All patients with iron deficiency should be screened for celiac disease regardless of gastrointestinal symptoms. 1

• Obtain tissue transglutaminase antibodies (anti-tTG) with total IgA level 1
• IgA measurement is essential because IgA deficiency makes serologic testing unreliable 1

Determining Need for GI Investigation

Patient Demographics Matter Critically

For postmenopausal women and all men: Upper and lower GI investigations should be performed unless there is significant overt non-GI blood loss, as GI malignancy may present with iron deficiency before frank anemia develops. 1

For premenopausal women: GI investigation should be based on:

• Age >45 years: Investigate per standard protocol 1
• Age <45 years: Investigate only if upper GI symptoms present OR if unable to maintain hemoglobin/iron stores with supplementation 1
• Heavy menstrual bleeding is the most common cause in this population 1, 2

Recommended GI Workup (When Indicated)

Upper endoscopy with duodenal biopsies (for celiac disease) should be performed first 1

Lower GI investigation (colonoscopy preferred over CT colonography or barium enema) should follow unless:

• Advanced gastric cancer is found, OR
• Celiac disease is found in patient <50 years without marked anemia or family history of colorectal cancer 1

Important caveat: Dual pathology (bleeding sources in both upper and lower GI tracts) occurs in 1-10% of patients, particularly in older individuals. 1

Monitoring and Follow-Up

Short-term Monitoring

• Hemoglobin should rise by 2 g/dL after 3-4 weeks of iron therapy 1
• Failure to respond indicates: poor compliance, misdiagnosis, continued blood loss, or malabsorption 1

Long-term Monitoring

Once normalized, monitor hemoglobin and red cell indices:

• Every 3 months for the first year 1
• At 2 years 1
• Check ferritin if hemoglobin or MCV falls below normal 1

Further investigation is only necessary if hemoglobin and MCV cannot be maintained with iron supplementation. 1

When to Consider Parenteral Iron

Intravenous iron should be reserved for: 1, 2

• Intolerance to at least two oral iron preparations
• Malabsorption conditions (celiac disease, post-bariatric surgery)
• Ongoing blood loss exceeding absorption capacity
• Chronic inflammatory conditions (IBD, CKD, heart failure)
• Pregnancy (second and third trimesters)

Critical Pitfalls to Avoid

Do not perform fecal occult blood testing - it is insensitive and non-specific for investigating iron deficiency 1

Do not delay investigation in men or postmenopausal women - even borderline iron deficiency may represent early presentation of GI malignancy 1

Do not stop at finding one lesion - dual pathology is common, particularly in older patients 1

Do not assume menstrual loss explains everything in premenopausal women >45 years - investigate per standard protocol 1