2023 Aug 17. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan–.
ABSTRACT
Anemia is a condition characterized by a deficiency in the number of circulating red blood cells (RBCs), the amount of hemoglobin (Hgb), or the volume of packed RBCs (hematocrit). The World Health Organization defines anemia as a hemoglobin level below 13 g/dL in men and below 12 g/dL in women.
Anemia can be classified into 2 main types: acute and chronic.
Acute anemia is a sudden and rapid decrease in RBCs, primarily caused by hemolysis or acute hemorrhage.
Chronic anemia is characterized by a gradual decline in RBCs over time. The causes of chronic anemia are diverse and can include conditions such as iron or other nutritional deficiencies, chronic diseases, drug-induced factors, and other underlying causes.