What is the appropriate workup and management for a patient with iron (Fe) deficiency anemia, considering their medical history, demographics, and potential underlying conditions?

Workup for Iron Deficiency Anemia

All adult men and postmenopausal women with confirmed iron deficiency anemia require bidirectional endoscopy (upper and lower GI evaluation) to exclude gastrointestinal malignancy, along with celiac disease screening, regardless of symptoms. 1

Diagnostic Confirmation

Establish the diagnosis first:

• Hemoglobin thresholds: <13 g/dL in men or <12 g/dL in non-pregnant women 1
• Ferritin <45 ng/mL confirms iron deficiency in patients without inflammation 1
• In patients with chronic inflammatory conditions (CKD, IBD, heart failure), ferritin may be elevated; use ferritin <100 ng/mL or transferrin saturation <20% to diagnose iron deficiency 1, 2
• Consider hemoglobin electrophoresis in patients of appropriate ethnic background with microcytosis to exclude thalassemia before proceeding with GI workup 1

Initial Workup Steps

Screen all patients for celiac disease with serologic testing (anti-endomysial or anti-tissue transglutaminase antibodies) 1

Test for Helicobacter pylori non-invasively (urea breath test or stool antigen) 1

Obtain detailed history focusing on:

• NSAID/aspirin use (stop if possible) 1
• Dietary iron intake 1
• Menstrual blood loss patterns in premenopausal women 1
• Family history of GI malignancy, bleeding disorders, or hereditary telangiectasia 1

Gastrointestinal Evaluation

For Men and Postmenopausal Women

Perform bidirectional endoscopy (upper endoscopy with duodenal biopsies AND colonoscopy) 1:

• Upper endoscopy: Obtain small bowel biopsies even if mucosa appears normal, as 2-3% of patients have celiac disease 1
• Lower GI evaluation: Colonoscopy is preferred over CT colonography or barium enema for detecting angiodysplasia and allowing tissue sampling 1
• Do not stop at upper GI findings alone unless advanced gastric cancer or celiac disease is found—dual pathology occurs in 10-15% of patients 1

Important caveat: Oesophagitis, gastric erosions, or peptic ulcers found on upper endoscopy should NOT deter lower GI investigation, as these are uncommon causes of chronic occult bleeding 1

For Premenopausal Women

Clinical judgment determines extent of workup 1:

• All should be screened for celiac disease 1
• If younger with clear menstrual blood loss explanation and no alarm features, consider empiric iron supplementation trial first 1
• Proceed with bidirectional endoscopy if:
  • Age >50 years 1
  • Marked anemia 1
  • Family history of colorectal cancer 1
  • Failure to respond to iron therapy 1
  • GI symptoms present 1

Further Evaluation (When Initial Workup Negative)

Small bowel evaluation is NOT routinely needed unless 1:

• Transfusion-dependent anemia 1
• Ongoing visible blood loss (melena) 1
• Symptoms suggesting small bowel disease 1
• Hemoglobin cannot be restored/maintained with iron therapy 1

If small bowel evaluation indicated:

• Video capsule endoscopy is reasonable after unrevealing bidirectional endoscopy 1
• Deep enteroscopy with distal attachment for suspected angioectasias 1

Additional testing in refractory cases:

• Eradicate H. pylori if present in patients with recurrent IDA and normal endoscopies 1
• Consider urinalysis to exclude urinary tract bleeding 1

What NOT to Do

Avoid faecal occult blood testing—it is insensitive and non-specific, providing no diagnostic value 1

Do not perform routine liver function, renal function, or clotting studies unless history suggests systemic disease 1

Do not accept dietary deficiency alone as explanation without completing GI evaluation in at-risk populations 1

Treatment Initiation

Start oral iron supplementation immediately while workup proceeds 1:

• Ferrous sulfate 325 mg daily (65 mg elemental iron) or alternate-day dosing for better absorption 2, 3
• Continue for 3 months after anemia correction to replenish stores 1
• Intravenous iron indicated for: oral intolerance, malabsorption (celiac disease, post-bariatric surgery), inflammatory conditions (IBD, CKD, heart failure), ongoing blood loss, or pregnancy (second/third trimester) 1, 2, 3

Follow-Up Monitoring

Reassess in 2-4 weeks to confirm response to oral iron 3

Once normalized, monitor hemoglobin and MCV:

• Every 3 months for 1 year 1
• Then annually 1
• Further investigation only if hemoglobin/MCV cannot be maintained with supplementation 1