Anemia, also called anaemia, is a syndrome defined by a low level of hemoglobin in the blood.
Hemoglobin is the dominant protein of RBCs (Red Blood Cells) that allows transport of oxygen to the tissues. A deficiency of hemoglobin results in a lack of oxygen throughout the body. The amount of hemoglobin necessary for a proper function of the oxygen transport depends on the age, sex, altitude and other circumstances such as pregnancy or smoking.
WHO (World Health Organization) defines anemia when the hemoglobin concentration in the blood is less than:
|Children from 6 month to 6 years old||<11 g/dl|
|Children from 6 to 14 years old||<12 g/dl|
|Men||< 13 g/dl|
|Non-pregnant women||< 12 g/dl|
|Pregnant women||< 11 g/dl|
Anemia produces a range of symptoms that may vary depending on the cause. Symptoms may include:
Besides, in case of severe anemia the following symptoms may be present:
Anemia can happen by multiple causes. RBCs size differs depending on the type of anemia. The size of the RBCs is measured by a parameter called MCV (Mean Corpuscular Volume). The MCV allows a classification for the different types of anemia.
RBCs are smaller than usual. It is a feature of the following types of anemia:
RBCs are relatively normal in size. It can be seen in the following types of anemia:
There are abnormally large RBCs in size. Macrocytic anemia can be classified as:
The most common types of anemia, defined by a decreased level of hemoglobin in the blood, are the following ones:
Iron-deficiency anemia is due to a lack of iron in the body. The lack of iron can be caused by:
Thalassemia is a type of anemia caused by alteration in the synthesis of the hemoglobin. Altered hemoglobin cannot carry enough oxygen to the body cells. It is an inherited disease caused by a genetic disorder.
Anemia of chronic disease is caused by chronic diseases related to the kidneys, digestive system, etc.
Hemolytic anemia is caused by a qualitative or intrinsic defect of red blood cells (RBCs). RBCs have normally a biconcave shape. In hemolytic anemias RBCs have a different shape and they are usually destroyed before their normal life span.
They can be caused by transfusions, toxic substances, etc.
In aplastic anemia the bone marrow does not produce enough red blood cells (RBCs) or the RBCs produced are immature with an altered function.
Megaloblastic anemia is caused by the lack of folic acid or vitamin B12, two substances required for the production of RBCs.
The lack of these substances may be due to a deficit in the diet or due to an excessive loss related to gastrointestinal disorders.
In case of suffering from anemia it is necessary to visit the doctor. When the anemia is considered an emergency requires an urgent visit to the medical facilities. Sometimes it is not an emergency, but it must be considered by a specialist.
Poor clinical or hemodynamic evolution due to exacerbation of the underlying disease (in general hemoglobin below 7-8 g/dl is well tolerated).