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Chapters

0:00 Introduction
0:55 Causes of Anemia
2:11 Symptoms of Anemia
2:53 Diagnosis of Anemia
3:28 Treatment of Anemia


Anemia, also spelled anaemia and sometimes called erythrocytopenia,[a] is a decrease in the total amount of red blood cells (RBCs) or hemoglobin in the blood[3][4] or a lowered ability of the blood to carry oxygen.[5] When anemia comes on slowly, the symptoms are often vague and may include feeling tired, weakness, shortness of breath, and a poor ability to exercise.[1] When the anemia comes on quickly, symptoms may include confusion, lightheadedness, loss of consciousness, and increased thirst.[1] Anemia must be significant before a person becomes noticeably pale.[1] Additional symptoms may occur depending on the underlying cause.[1] For people who require surgery, pre-operative anemia can increase the risk of requiring a blood transfusion following surgery.[6]

Anemia can be caused by bleeding, decreased red blood cell production, and increased red blood cell breakdown.[1] Causes of bleeding include trauma and gastrointestinal bleeding.[1] Causes of decreased production include iron deficiency, vitamin B12 deficiency, thalassemia and a number of neoplasms of the bone marrow.[1] Causes of increased breakdown include genetic conditions such as sickle cell anemia, infections such as malaria, and certain autoimmune diseases.[1] Anemia can also be classified based on the size of the red blood cells and amount of hemoglobin in each cell.[1] If the cells are small, it is called microcytic anemia; if they are large, it is called macrocytic anemia; and if they are normal sized, it is called normocytic anemia.[1] The diagnosis of anemia in men is based on a hemoglobin of less than 130 to 140 g/L (13 to 14 g/dL); in women, it is less than 120 to 130 g/L (12 to 13 g/dL).[1][7] Further testing is then required to determine the cause.[1][8]

Certain groups of individuals, such as pregnant women, benefit from the use of iron pills for prevention.[1][9] Dietary supplementation, without determining the specific cause, is not recommended.[1] The use of blood transfusions is typically based on a person's signs and symptoms.[1] In those without symptoms, they are not recommended unless hemoglobin levels are less than 60 to 80 g/L (6 to 8 g/dL).[1][10] These recommendations may also apply to some people with acute bleeding.[1] Erythropoiesis-stimulating agents are only recommended in those with severe anemia.[10]

Anemia is the most common blood disorder, affecting about a third of the global population.[1][2][11] Iron-deficiency anemia affects nearly 1 billion people.[12] In 2013, anemia due to iron deficiency resulted in about 183,000 deaths – down from 213,000 deaths in 1990.[13] This condition is more common in women than men,[12] during pregnancy, and in children and the elderly.[1] Anemia increases costs of medical care and lowers a person's productivity through a decreased ability to work.[7] The name is derived from Ancient Greek: ἀναιμία anaimia, meaning "lack of blood", from ἀν- an-, "not" and αἷμα haima, "blood".[14]

Anemia is one of the six WHO global nutrition targets for 2025 and diet-related global NCD targets for 2025, endorsed by World Health Assembly in 2012 and 2013. Efforts to reach global targets contribute to reaching Sustainable Development Goals (SDGs),[15] with anemia as one of the targets in SDG 2.[16]