Iron Deficiency Anemia Diagnosis

Key Laboratory Features

The American Gastroenterological Association suggests that an elevated RDW-CV (16.9%, reference range 11.0-15.0%) strongly indicates iron deficiency anemia rather than thalassemia trait 1, 2
The European Crohn’s and Colitis Organisation recommends that in patients with microcytosis (MCV <70 fL), an RDW coefficient of variation >14.0% is indicative of iron deficiency anemia 1
The World Gastroenterology Organisation notes that microcytosis (MCV 72.2 fL) combined with low MCH (22.6 pg) and mild anemia (Hb 11.3 g/dL) fits the classic pattern of iron deficiency 3, 4

The British Society of Gastroenterology recommends that serum ferritin is the single most powerful test and must be obtained immediately to confirm iron deficiency 3, 4, 5
The American College of Gastroenterology suggests that a ferritin <30 μg/L confirms iron deficiency in the absence of inflammation; <100 μg/L may still indicate iron deficiency if inflammation is present 3, 6
The European Society for Clinical Nutrition and Metabolism recommends that transferrin saturation should be measured simultaneously with ferritin and CRP to assess for functional iron deficiency 2, 7

The National Institute for Health and Care Excellence recommends ordering serum ferritin, transferrin saturation, and CRP immediately to diagnose iron deficiency anemia 2, 3, 7
The American Gastroenterological Association suggests that if ferritin confirms iron deficiency (<30 μg/L), investigate the source (gastrointestinal blood loss, dietary inadequacy, malabsorption including celiac disease) 2, 4
The World Gastroenterology Organisation recommends that if ferritin is normal (>100 μg/L), proceed to hemoglobin electrophoresis to exclude thalassemia trait, though this is unlikely given the elevated RDW 1, 3