Definition and Overview
- Anemia is a blood disorder characterized by a reduced ability to carry oxygen due to a lower than normal number of red blood cells or abnormalities in hemoglobin.
- The name 'anemia' is derived from the Greek words meaning 'lack of blood.'
- Symptoms of anemia include tiredness, weakness, shortness of breath, headaches, and reduced ability to exercise.
- Anemia can be temporary or long term, and its severity can range from mild to severe.
- Causes of anemia include blood loss, decreased red blood cell production, and increased red blood cell breakdown.
Types and Classification
- Anemia can be classified based on the size of red blood cells and the amount of hemoglobin in each cell.
- Microcytic anemia refers to small red blood cells, macrocytic anemia refers to large red blood cells, and normocytic anemia refers to normal-sized red blood cells.
- Anemia can also be classified based on the underlying cause, such as iron deficiency, vitamin B deficiency, thalassemia, genetic disorders, infections, or autoimmune diseases.
- Diagnosis of anemia is based on hemoglobin levels, with different thresholds for men and women.
- Further testing is required to determine the specific cause of anemia.
Signs and Symptoms
- Symptoms of anemia may vary depending on the underlying cause and the severity of the condition.
- Common symptoms include tiredness, weakness, decreased ability to concentrate, and shortness of breath on exertion.
- Other symptoms may include dizziness, headaches, irregular or rapid heartbeat, pale or yellow skin, poor appetite, easy bruising and bleeding, and muscle weakness.
- Severe anemia can lead to symptoms like feeling faint, chest pain, sweating, increased thirst, and confusion.
- Physical examination may reveal signs such as pallor, blue sclera, koilonychia, jaundice, nerve cell damage, bone deformities, leg ulcers, tachycardia, and signs of heart failure.
Causes and Risk Factors
- Impaired red blood cell production, increased red blood cell destruction, blood loss, and fluid overload are the main causes of anemia.
- Blood loss can result from inflammation, surgery, injury, or donation.
- Decreased production can be caused by deficiencies in iron or vitamin B, thalassemia, or bone marrow tumors.
- Increased breakdown can be due to genetic disorders, infections like malaria, or autoimmune diseases.
- Certain groups, such as pregnant women, are at higher risk of developing anemia.
Treatment and Prevention
- Treatment of anemia depends on the underlying cause and severity.
- Iron pills may be beneficial for certain groups, like pregnant women, to prevent anemia.
- Dietary supplementation without determining the specific cause is not recommended.
- Blood transfusions may be necessary in individuals with severe anemia or those experiencing acute bleeding.
- Erythropoiesis-stimulating agents are recommended for severe anemia cases.
Anemia or anaemia (British English) is a blood disorder in which the blood has a reduced ability to carry oxygen due to a lower than normal number of red blood cells, a reduction in the amount of hemoglobin or hemoglobin abnormalities. The name is derived from Ancient Greek: ἀναιμία anaimia, meaning 'lack of blood', from ἀν- an-, 'not' and αἷμα haima, 'blood'. When anemia comes on slowly, the symptoms are often vague, such as tiredness, weakness, shortness of breath, headaches, and a reduced ability to exercise. When anemia is acute, symptoms may include confusion, feeling like one is going to pass out, loss of consciousness, and increased thirst. Anemia must be significant before a person becomes noticeably pale. Symptoms of anemia depend on how quickly hemoglobin decreases. Additional symptoms may occur depending on the underlying cause. Preoperative anemia can increase the risk of needing a blood transfusion following surgery. Anemia can be temporary or long term and can range from mild to severe.
| Anemia | |
|---|---|
| Other names | Anaemia, erythrocytopenia |
 | |
| Blood smear showing iron-deficiency anemia, with small, pale red blood cells. | |
| Pronunciation | |
| Specialty | Hematology |
| Symptoms | Feeling tired, pale skin, weakness, shortness of breath, feeling faint |
| Causes | Blood loss, decreased red blood cell production, increased red blood cell breakdown |
| Diagnostic method | Blood hemoglobin measurement |
| Frequency | 2.36 billion / 33% (2015) |
Anemia can be caused by blood loss, decreased red blood cell production, and increased red blood cell breakdown. Causes of bleeding include bleeding due to inflammation of the stomach or intestines, bleeding from surgery, serious injury, or blood donation. Causes of decreased production include iron deficiency, vitamin B12 deficiency, thalassemia and a number of bone marrow tumors. Causes of increased breakdown include genetic disorders such as sickle cell anemia, infections such as malaria, and certain autoimmune diseases. Anemia can also be classified based on the size of the red blood cells and amount of hemoglobin in each cell. 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. 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). Further testing is then required to determine the cause.
A large number of patients diagnosed with anemia of chronic disease present with no active inflammation or dietary issues. These include many with reduced limb loading, such as spinal cord injured patients, astronauts, elderly people with limited mobility, bed-bound and experimental bed-rest subjects.
Certain groups of individuals, such as pregnant women, benefit from the use of iron pills for prevention. Dietary supplementation, without determining the specific cause, is not recommended. The use of blood transfusions is typically based on a person's signs and symptoms. In those without symptoms, they are not recommended unless hemoglobin levels are less than 60 to 80 g/L (6 to 8 g/dL). These recommendations may also apply to some people with acute bleeding. Erythropoiesis-stimulating agents are only recommended in those with severe anemia.
Anemia is the most common blood disorder, affecting about a fifth to a third of the global population. Iron-deficiency anemia affects nearly 1 billion people. In 2013, anemia due to iron deficiency resulted in about 183,000 deaths – down from 213,000 deaths in 1990. This condition is most prevalent in children with also an above average prevalence in elderly and women of reproductive age (especially during pregnancy).
Anemia is one of the six WHO global nutrition targets for 2025 and for diet-related global targets endorsed by World Health Assembly in 2012 and 2013. Efforts to reach global targets contribute to reaching Sustainable Development Goals (SDGs), with anemia as one of the targets in SDG 2 for achieving zero world hunger.
