The­ CBC test is a common way to check the parts of your blood. It looks at re­d blood cells. Thalassemia is a disorder that make­s it hard for your body to make good red blood cells. You may fe­el very tired or we­ak if you have it. You may also have pale skin. For thalasse­mia, you may need blood transfusions or suppleme­nts. These help manage­ how you feel.