Your doctor will diagnose anemia based on your medical and family histories, a physical exam, and results from tests and procedures.
                
Because anemia doesn't always cause symptoms, your doctor may find out you have it while checking for another condition.
                
Medical and Family Histories
                
Your doctor may ask whether you have any of the common signs or symptoms of anemia. He or she also may ask whether you've had an illness or condition that could cause anemia.
                
Let your doctor know about any medicines you take, what you typically eat (your diet), and whether you have family members who have anemia or a history of it.
                
Physical Exam
                
Your doctor will do a physical exam to find out how severe your anemia is and to check for possible causes. He or she may:
                
Listen to your heart for a rapid or irregular heartbeat
                
Listen to your lungs for rapid or uneven breathing
                
Feel your abdomen to check the size of your liver and spleen
                
Your doctor also may do a pelvic or rectal exam to check for common sources of blood loss.
                
Diagnostic Tests and Procedures
                
You may have various blood tests and other tests or procedures to find out what type of anemia you have and how severe it is.
                
Complete Blood Count
                
Often, the first test used to diagnose anemia is a complete blood count (CBC). The CBC measures many parts of your blood.
                
The test checks your hemoglobin and hematocrit (hee-MAT-oh-crit) levels. Hemoglobin is the iron-rich protein in red blood cells that carries oxygen to the body. Hematocrit is a measure of how much space red blood cells take up in your blood. A low level of hemoglobin or hematocrit is a sign of anemia.
                
The normal range of these levels might be lower in certain racial and ethnic populations. Your doctor can explain your test results to you.
                
The CBC also checks the number of red blood cells, white blood cells, and platelets in your blood. Abnormal results might be a sign of anemia, another blood disorder, an infection, or another condition.
                
Finally, the CBC looks at mean corpuscular (kor-PUS-kyu-lar) volume (MCV). MCV is a measure of the average size of your red blood cells and a clue as to the cause of your anemia. In iron-deficiency anemia, for example, red blood cells usually are smaller than normal.
                
Other Tests and Procedures
                
If the CBC results show that you have anemia, you may need other tests, such as:
                
Hemoglobin electrophoresis (e-lek-tro-FOR-e-sis). This test looks at the different types of hemoglobin in your blood. The test can help diagnose the type of anemia you have.
                
A reticulocyte (re-TIK-u-lo-site) count. This test measures the number of young red blood cells in your blood. The test shows whether your bone marrow is making red blood cells at the correct rate.
                
Tests for the level of iron in your blood and body. These tests include serum iron and serum ferritin tests. Transferrin level and total iron-binding capacity tests also measure iron levels.
                
Because anemia has many causes, you also might be tested for conditions such as kidney failure, lead poisoning (in children), and vitamin deficiencies (lack of vitamins, such as B12 and folic acid).
                
If your doctor thinks that you have anemia due to internal bleeding, he or she may suggest several tests to look for the source of the bleeding. A test to check the stool for blood might be done in your doctor's office or at home. Your doctor can give you a kit to help you get a sample at home. He or she will tell you to bring the sample back to the office or send it to a laboratory.
                
If blood is found in the stool, you may have other tests to find the source of the bleeding. One such test is endoscopy (en-DOS-ko-pe). For this test, a tube with a tiny camera is used to view the lining of the digestive tract.
                
Your doctor also may want to do bone marrow tests. These tests show whether your bone marrow is healthy and making enough blood cells.