Chapter 3: Hypochromic Anaemias

At the forefront is iron deficiency, identified as the most prevalent cause of anaemia globally, affecting hundreds of millions of people, particularly in resource-limited regions or where parasitic infections are endemic. The text provides a deep dive into the physiological lifecycle of iron, explaining how the body utilizes transport proteins like transferrin and storage complexes such as ferritin and haemosiderin to maintain balance. A critical focus is placed on hepcidin, the master regulatory hormone produced by the liver, which controls iron levels by interacting with ferroportin to manage iron absorption in the gut and its release from macrophages. The narrative explains how the body's iron requirements fluctuate based on age, sex, and life stages such as pregnancy or rapid growth. Clinical recognition of iron deficiency involves identifying physical signs like brittle, spoon-shaped nails (koilonychia), tongue inflammation (glossitis), and sores at the corners of the mouth (angular stomatitis). For a definitive diagnosis, medical professionals look at red cell indices, specifically a reduction in mean corpuscular volume (MCV) and mean corpuscular haemoglobin (MCH), alongside low serum ferritin and a high total iron-binding capacity. The chapter also provides a vital differential diagnosis between simple iron deficiency and the anaemia of chronic disease, where inflammation-induced hepcidin blocks iron utilization despite adequate body stores. Treatment strategies emphasize identifying the underlying cause—such as gastrointestinal bleeding or menstruation—while replenishing iron through oral supplements like ferrous sulphate or, in more severe cases, parenteral intravenous iron. Finally, the discussion touches on rarer conditions including sideroblastic anaemia, which involves a defect in haem synthesis resulting in ringed iron deposits in the bone marrow, and lead poisoning, which inhibits multiple stages of blood cell production.