Haematinic Screening and Diagnosis

Core Components

A standard haematinic screen should include a complete blood count (CBC) with red cell indices, serum ferritin, transferrin saturation, and vitamin B12 and folate levels, as recommended by the American College of Physicians 1, 2
Hemoglobin concentration and hematocrit are commonly used screening tests, but are late indicators of iron deficiency, according to the Centers for Disease Control and Prevention 3, 4
Mean corpuscular volume (MCV) measures the average red blood cell size and is essential for classifying anemia, with a normal range of 80-100 fL 1
Red cell distribution width (RDW) is critical for detecting mixed deficiencies, with an elevated RDW (>14.0%) suggesting iron deficiency anemia 1
Mean corpuscular hemoglobin (MCH) provides a sensitive indication of iron deficiency, with low levels indicating iron depletion 2
Reticulocyte count helps distinguish between production defects and hemolysis or blood loss, with elevated reticulocytes indicating increased red blood cell production 5, 1

Serum ferritin is the most powerful single test for diagnosing iron deficiency, with levels <30 μg/L indicating iron deficiency, according to the National Institute of Diabetes and Digestive and Kidney Diseases 1, 2
Transferrin saturation represents iron available for erythropoiesis, with <20% indicating functional or absolute iron deficiency, as recommended by the Kidney Disease: Improving Global Outcomes (KDIGO) guidelines 5, 1
Serum iron and total iron-binding capacity (TIBC) are measured together to calculate transferrin saturation, with low serum iron and high TIBC indicating iron deficiency 3

Ferritin is an acute-phase reactant and may be falsely elevated in inflammatory conditions, requiring a higher threshold (<100 μg/L) to diagnose iron deficiency, according to the European Renal Association 5, 2
C-reactive protein (CRP) should be measured alongside ferritin to assess for inflammation that could confound interpretation, as recommended by the American College of Physicians 1

Erythrocyte protoporphyrin concentration detects earlier changes in iron status than hemoglobin or hematocrit, with elevated levels indicating iron deficiency, according to the Centers for Disease Control and Prevention 3
Soluble transferrin receptor (sTfR) may help distinguish iron deficiency anemia from anemia of chronic disease, particularly in patients with liver disease or inflammatory conditions, as recommended by the American Association for the Study of Liver Diseases 1
Percent hypochromic red blood cells (PHRBC) and content of hemoglobin in reticulocytes (CHr) are specialized tests with high sensitivity and specificity for functional iron deficiency, though they require expensive equipment, according to the International Society of Nephrology 5

Do not rely solely on MCV for classification, as coexisting conditions may neutralize MCV changes, according to the American College of Physicians 1
Do not misinterpret ferritin without considering inflammatory status, as this leads to incorrect diagnosis in patients with chronic disease, as recommended by the European Renal Association 1, 2
Do not fail to investigate underlying causes of deficiencies, particularly gastrointestinal bleeding in iron deficiency, according to the American Gastroenterological Association 1