What is the appropriate management for a patient with severe iron deficiency anemia (Hemoglobin level of 7.4 g/dL), considering potential gastrointestinal disorders or other underlying causes?

Management of Severe Iron Deficiency Anemia (Hemoglobin 7.4 g/dL)

Immediately initiate oral iron supplementation with ferrous sulfate 200 mg three times daily while simultaneously pursuing urgent gastrointestinal evaluation to identify the underlying cause, as this degree of anemia warrants fast-track investigation for potentially serious pathology including malignancy. 1

Immediate Iron Replacement Therapy

• Start ferrous sulfate 200 mg (65 mg elemental iron) three times daily as first-line treatment, which is the most cost-effective and widely available option 1
• Alternative ferrous salts (ferrous gluconate or ferrous fumarate) are equally effective if ferrous sulfate is not tolerated 1
• Add ascorbic acid (vitamin C) 500 mg with iron doses to enhance absorption, particularly if response is suboptimal 1
• Take iron on an empty stomach for optimal absorption, though taking with meals is acceptable if gastrointestinal side effects occur 1
• Expect hemoglobin to rise by 2 g/dL (20 g/L) within 3-4 weeks if treatment is effective 1
• Continue iron supplementation for 3 months after hemoglobin normalizes to replenish iron stores 1

When to Use Intravenous Iron

• Consider IV iron if oral iron fails after 3-4 weeks, which indicates intolerance, malabsorption, continued blood loss, or misdiagnosis 1
• IV iron is appropriate for patients with intolerance to at least two oral preparations 1
• Severe ongoing blood loss exceeding intestinal absorption capacity warrants IV iron 2
• Note that IV iron does not produce faster hemoglobin rise than oral preparations, but ensures delivery when oral route fails 1

Urgent Diagnostic Evaluation

Confirm Iron Deficiency

• Measure serum ferritin as the single most useful marker; levels <15 μg/L indicate absent iron stores, while <30 μg/L suggests low stores 1
• Use ferritin cut-off of <45 ng/mL for optimal sensitivity and specificity in anemic patients 1
• Check transferrin saturation if ferritin is equivocal or inflammation is suspected (ferritin is an acute phase reactant) 1
• Review mean corpuscular volume (MCV) and mean corpuscular hemoglobin (MCH); MCH may be more sensitive than MCV for iron deficiency 1

Critical Pitfall to Avoid

Do not assume dietary deficiency or menstrual loss as the sole cause without investigation—with hemoglobin of 7.4 g/dL, gastrointestinal pathology including malignancy must be excluded 1

Gastrointestinal Investigation Protocol

For Men and Postmenopausal Women (Strong Recommendation)

• Perform bidirectional endoscopy (upper endoscopy with small bowel biopsies AND colonoscopy) as 10-15% have dual pathology 1
• Upper endoscopy identifies causes in 30-50% of cases 1
• Obtain small bowel biopsies during upper endoscopy as 2-3% have celiac disease 1
• Complete colonic evaluation is mandatory even if upper GI lesion is found, unless carcinoma or celiac disease is identified 1
• This hemoglobin level (<110 g/L) warrants fast-track referral per NICE guidelines for suspected GI malignancy 1

For Premenopausal Women

• Women over age 45 should undergo full bidirectional endoscopy regardless of menstrual status due to increasing cancer risk 1
• Women under 45 with upper GI symptoms require upper endoscopy with small bowel biopsies 1
• For asymptomatic women under 45, test for celiac disease (anti-endomysial antibodies with IgA level) and H. pylori non-invasively before considering endoscopy 1
• However, severe anemia (Hb 7.4 g/dL) increases likelihood of serious pathology and lowers the threshold for full investigation even in younger women 1

Non-Invasive Testing First

• Test for H. pylori and celiac disease before endoscopy in appropriate patients 1
• Measure IgA level with anti-endomysial antibodies to avoid false-negative results in IgA deficiency 1
• If these tests are positive, treat accordingly and reassess response 1

Additional Diagnostic Considerations

• Obtain detailed dietary history, though borderline deficient diets should not preclude full GI investigation 1
• Document use of NSAIDs, aspirin, and anticoagulants; stop NSAIDs if possible but do not defer investigation 1
• Check for hematuria to exclude rare urinary tract tumors 1
• Consider Hb electrophoresis if microcytosis is present with normal iron studies, particularly in appropriate ethnic backgrounds, to exclude thalassemia 1

Monitoring Response to Treatment

• Recheck hemoglobin after 2 weeks; a rise ≥10 g/L strongly confirms iron deficiency even if initial iron studies were equivocal 1
• If hemoglobin fails to rise by 2 g/dL after 3-4 weeks, consider: poor compliance, misdiagnosis, continued blood loss, or malabsorption 1
• Monitor hemoglobin and MCV every 3 months for one year after normalization, then annually 1
• Target resolution of anemia within 6 months in 80% of patients 1

Further Evaluation if Initial Workup is Negative

• Video capsule endoscopy is reasonable for patients on antiplatelet/anticoagulant therapy with unrevealing bidirectional endoscopy 1
• Deep enteroscopy with distal attachment should be performed if small bowel bleeding or angioectasias are suspected 1
• Small bowel radiology is rarely useful unless Crohn's disease is suspected 1
• Further small bowel visualization is generally unnecessary unless anemia is transfusion-dependent or visible blood loss occurs 1

Common Pitfalls

• Do not accept oesophagitis, erosions, or peptic ulcer as the sole cause without completing colonic evaluation, as dual pathology is common 1
• Ferritin may be falsely normal in inflammatory conditions; use transferrin saturation <20% or other markers if inflammation is suspected 1
• Failure to continue iron for 3 months after hemoglobin normalizes leads to inadequate store repletion and recurrence 1
• Enteric-coated or sustained-release iron preparations should be avoided as they reduce absorption 3