Diagnostic and Treatment Approach for Anemia with Normal Liver Function
Start oral iron supplementation immediately with ferrous sulfate 200 mg once daily while simultaneously investigating the underlying cause—do not delay treatment while awaiting diagnostic workup. 1
Immediate Diagnostic Workup
Confirm Iron Deficiency
- Serum ferritin is your single most powerful diagnostic test 1, 2
- Check transferrin saturation: <20% supports iron deficiency 3
- Obtain complete blood count with MCV and red cell distribution width 3, 4
Essential Initial Investigations
All patients require: 1
- Urinalysis or urine microscopy (to exclude renal blood loss)
- Celiac disease screening (found in 3-5% of iron deficiency anemia cases) 1
- Detailed dietary history focusing on iron intake, though borderline deficient diets alone should not stop further investigation 2
- Medication review: NSAIDs, aspirin, anticoagulants 5, 2
Gastrointestinal Evaluation
For men and postmenopausal women with confirmed iron deficiency anemia, bidirectional endoscopy is first-line: 1
- Gastroscopy AND colonoscopy with biopsies from both inflamed and uninflamed segments
- Obtain small bowel biopsies at gastroscopy to screen for celiac disease if serology not done 1
- CT colonography is acceptable if colonoscopy not feasible 1
For premenopausal women: Consider menstrual blood loss as primary cause, but if heavy menstrual bleeding is absent or anemia is severe, proceed with GI evaluation 6
Treatment Algorithm
First-Line: Oral Iron
Start with ferrous sulfate 200 mg once daily (not twice daily—once daily or alternate-day dosing is equally effective and better tolerated) 1
Alternative oral preparations if not tolerated:
- Ferrous fumarate
- Ferrous gluconate
- Lower dose (one tablet every other day) 1
Optimize absorption:
Monitor response at 4 weeks: Expect hemoglobin rise ≥10 g/L within 2 weeks; this response itself confirms iron deficiency even if iron studies were equivocal 1
Continue for 3 months after hemoglobin normalizes to replenish iron stores 1, 5
Second-Line: Intravenous Iron
Switch to IV iron if: 1
- Oral iron not tolerated
- Inadequate response to oral iron
- Severe anemia requiring rapid correction
- Malabsorption (e.g., celiac disease, inflammatory bowel disease)
IV iron options:
- Iron sucrose (200 mg over 10 minutes) 5
- Ferric carboxymaltose (up to 1000 mg over 15 minutes) 5
- Iron dextran (requires longer infusion, higher risk of serious reactions) 5
Red Blood Cell Transfusion
Reserve transfusion for: 1
- Hemodynamic instability
- Symptomatic anemia with comorbidities requiring higher hemoglobin
- Need for acute hemoglobin increase (pre-surgery, pregnancy)
- Iron replacement still required post-transfusion 1
If Initial Workup is Negative
When gastroscopy and colonoscopy are negative but anemia persists or recurs: 1
Investigate small bowel:
Test for Helicobacter pylori and eradicate if present (can impair iron absorption) 5
Renal tract imaging if hematuria present 1
Consider hematology referral if anemia without low ferritin (to exclude other causes) 6
Special Considerations
Anemia of Chronic Disease (with normal liver function)
- Ferritin >100 μg/L AND transferrin saturation <20% suggests anemia of chronic disease 3
- Ferritin 30-100 μg/L suggests mixed picture 3
- Still treat with iron if ferritin <100 μg/L 3
If No Cause Found
Long-term iron replacement is appropriate when cause is unknown or irreversible 1
Critical Pitfalls to Avoid
- Do not delay iron therapy while investigating—start treatment immediately 1
- Do not assume dietary deficiency alone—always complete GI evaluation in men and postmenopausal women 2
- Do not stop at negative bidirectional endoscopy if anemia recurs—investigate small bowel 1
- Do not use ferritin alone in inflammatory states—add transferrin saturation 3
- Do not forget celiac screening—present in 3-5% of cases 1