Macrocytic Anemia

Introduction

Macrocytic anaemia is characterised by enlarged red blood cells with a mean corpuscular volume (MCV) greater than 100 fL. It is classified as megaloblastic or non-megaloblastic. Megaloblastic anaemia results from impaired DNA synthesis, most commonly because of vitamin B12 or folate deficiency or medicines that interfere with DNA synthesis. Non-megaloblastic macrocytic anaemia occurs without impaired DNA synthesis and is associated with conditions that alter red blood cell production or membrane composition. This article provides a step-by-step guide to distinguishing these categories, investigating their causes and managing affected patients.