Anemia

definition, epidemiology, pathophysiology, classification, clinical picture, and treatment

Abstract

Anemia is the reduction of hemoglobin mass and, consequently, of erythrocyte mass. Its result is tissue hypoxia. Anemia is the manifestation of an underlying illness, frequently not apparent. It affects more than one billion people around the world. Anemia can be classified based on several characteristics, however, in daily practice, the most used is the one based on the mean corpuscular volume of erythrocytes as microcytic, normocytic and macrocytic. The most prevalent types of anemia are iron deficient anemia and anemia secondary to inflammation. The iron deficiency anemia appears when the iron store is exhausted, most frequently due to chronic bleeding, for instance, augmented menorrhea and gastrointestinal bleeding. The anemia of inflammation is secondary to iron sequestration in macrophages, decreased erythropoiesis, and lower erythrocyte survival. Ferritin is decreased in the iron deficient anemia and increased in the anemia of inflammation. Other common types of anemia are those secondary to pregnancy, chronic renal failure, and ageing. Treatment of anemia depends on its type, such as iron supplementation or erythropoietin, among others. Red blood cell transfusion can be performed in more severe conditions, independently of the type of anemia, and must be adopted in diseases such as thalassemia major. This article reviews the prevalence of anemia, its classification, pathophysiology, and discusses the commonest types and treatment according to the type of anemia.