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Anemias

The anemias are a group of blood disorders characterized by too little
hemoglobin in the blood. Hemoglobin is a substance contained in red
blood cells that carries oxygen from the lungs to other body tissues. Anemia
is often a sign or symptom of an underlying disease rather than a disease in
its own right. There are three tests commonly used to detect anemia: the
number of red blood cells can be counted; the amount of hemoglobin in
the red blood cells can be measured; or the proportion of blood cells to
serum (the liquid part of blood, called the hematocrit) can be assessed.
Anemia can develop in three ways: loss of blood through injury, diseases
of the digestive tract, or heavy menstrual flow in women; rapid
destruction of red blood cells (for example in sickle cell anemia); or inadequate
production of healthy red blood cells (for example in thalassemia).
The underlying causes of anemias range from poor nutrition (iron-deficiency
anemia) and digestive disorders (Crohn disease, celiac disease) to
colorectal cancer, parasitic diseases (hookworm), and genetic disorders
(sickle cell anemia, thalassemia).
The anemias are the most common type of blood disorder in the general
population, affecting 4 percent of men and 8 percent of women in
the developed countries, and two to five times as many people in the
poorer nations.
SEE ALSO
Lead poisoning; Prematurity; Restless legs syndrome; Sickle cell anemia;
Thalassemia; Ulcers
Celiac disease; Colorectal cancer; Crohn disease; Heart failure;
Anemias
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