Diagnosis and Management of Iron Deficiency Anemia

Understanding Iron Deficiency Anemia

Elevated RDW reflects heterogeneous red cell populations with varying sizes as iron stores become depleted, making it a specific indicator of iron deficiency 1
Low MCHC indicates reduced hemoglobin concentration within red cells, which is characteristic of iron deficiency but can also occur in thalassemia 3
The combination of low MCHC and high RDW strongly favors iron deficiency over thalassemia, as thalassemia typically presents with low MCV and RDW ≤14.0%, while iron deficiency shows RDW >14.0% 2

Serum ferritin is the single most powerful test for iron deficiency: <15 μg/L indicates absent iron stores, <30 μg/L indicates low body iron stores 1, 2
Transferrin saturation <30% supports iron deficiency diagnosis and provides insight into circulating iron available for red cell production 1, 3
C-reactive protein (CRP) is essential to interpret ferritin correctly, as inflammation elevates ferritin and can mask true iron deficiency 1

All adult men and post-menopausal women with confirmed iron deficiency require gastrointestinal evaluation regardless of hemoglobin level or presence of symptoms 1, 2
Upper endoscopy with small bowel biopsies should be performed first: 30-50% will have an upper GI source identified, and 2-3% have celiac disease 1, 2, 3
Colonoscopy or CT colonography is mandatory even if upper GI source is found, as dual pathology occurs in approximately 10% of patients 1

Initiate oral iron supplementation once iron deficiency is confirmed by ferritin testing (or intravenous if malabsorption or intolerance present) 1
Continue iron for 3-6 months after hemoglobin normalizes to fully replete iron stores 1
Therapeutic response to 3 weeks of oral iron confirms the diagnosis when other tests are equivocal 2, 3

Never assume dietary insufficiency alone without completing GI evaluation—this can miss serious underlying pathology including malignancy 1, 3
Do not start empiric iron therapy without confirming iron deficiency, as this can cause harm in thalassemia patients and delays proper diagnosis 1
Ferritin is an acute phase reactant—it can be falsely normal or elevated during inflammation, infection, malignancy, or liver disease despite true iron deficiency 2