Several routine laboratory tests may be used to help diagnose anemia as well as help to determine the underlying cause. These are listed below. Depending on the results of these, the medical history of the person, and signs and symptoms, other tests may be done as follow up to help diagnose the cause of anemia and to help guide treatment. (Click on the links for the different types of anemia at the top of this page to read about these specific tests.)
Complete Blood Count (CBC)
Anemia may first be detected when a routine test that counts the number and relative proportion of each of the different types of cells in the blood stream, called a complete blood count (CBC), is done during a health exam or as part of testing for other conditions. A CBC is often ordered as part of a yearly physical exam and helps to evaluate overall health and to screen for a wide variety of disorders.
With anemia, some of the components of the CBC that may show abnormal results include:
- RBC count—typically low
- RBC indices—these include mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), and mean corpuscular hemoglobin concentration (MCHC). They give a healthcare practitioner information about the size of the red blood cells and the amount and concentration of hemoglobin in RBCs present in someone's blood at that moment. For example, the size and hemoglobin concentration of RBCs can help with diagnosing anemia because those characteristics can vary for different kinds of anemia.
Blood Smear and Differential
If results of the CBC indicate anemia, it may be followed up with an examination of a blood smear or a differential, which counts white blood cells. The smear review can provide additional information, such as the shape of red blood cells and the presence of abnormal cells, which can help diagnose and classify anemia.
This test provides information on the number of relatively immature red blood cells in a person's blood sample. When someone has anemia (low RBC count, hemoglobin, and hematocrit), the results of this test can help determine the cause and/or help classify the type of anemia. For example, for a person with anemia, an inappropriately low reticulocyte count often indicates decrease in red blood cell production in the bone marrow.
Results from these tests may give clues as to the cause. Several other tests may be run to help determine the cause of the anemia and to guide treatment. See the individual discussions of the different types of anemia for more on these.