Anemia is a condition that results from insufficient red blood cells or hemoglobin in the blood. Red blood cells take oxygen from the lungs and release it throughout the body. Hemoglobin is the iron-rich protein that carries oxygen inside the red blood cells and gives blood its red color.

There are many forms of anemia, including:
-- Iron deficiency anemia from lower than normal amounts of iron in the blood
-- Vitamin deficiency anemia due to lower than normal amounts of certain vitamins, like B-12, folate or vitamin C
-- Aplastic Anemia, which occurs when the bone marrow doesn’t produce enough red blood cells
-- Hemolytic Anemia, a condition in which the body destroys red blood cells prematurely
-- Sickle cell anemia, an inherited disorder characterized by abnormal, crescent-shaped red blood cells
-- Thalassemia, an inherited disorder in which the body produces an abnormal form of hemoglobin, leading to the premature destruction of red blood cells

How is anemia evaluated?
Common symptoms of anemia include fatigue, irritability, Headache and difficulty concentrating. Your physician may detect a heart murmur or note a significant decrease in your blood pressure when you stand. A blood sample will provide an overall count of your white blood cells, red blood cells and platelets. If results show anemia, additional tests may be required to determine the type of anemia and whether it is related to a more serious condition. Among these tests are:
-- hemoglobin electrophoresis to assess hemoglobin levels in your blood
-- a reticulocyte count to determine if your bone marrow is making red blood cells at the normal rate
-- serum iron and serum ferritin tests to check the amount of iron in your blood and body
-- a peripheral blood smear to see if anemia has caused the shape of your red blood cells to change
-- an osmotic fragility test to determine if your red blood cells have become more fragile than usual

Other, more invasive tests may be needed to search for the source of anemia. Your physician may order an endoscopy to visually examine your upper digestive system for signs of bleeding, or a colonoscopy or CT colonography to look for tumors and other problems in the large intestine and surrounding areas. Cell and bone marrow samples can provide clues to anemia-associated abnormalities.