Complete blood count; Anemia - CBC A complete blood count (CBC) test measures the following: The CBC test also provides information about the following measurements: The platelet count is also most often included in the CBC. Sickle cell anemia is an inherited blood disease in which the red blood cells produce abnormal pigment (hemoglobin). The abnormal hemoglobin causes deformity of the red blood cells into crescent or sickle-shapes, as seen in this photomicrograph.
This picture shows large, dense, oversized, red blood cells (RBCs) that are seen in megaloblastic anemia. Megaloblastic anemia can occur when there is a deficiency of vitamin B-12.
This photomicrograph shows one of the abnormal shapes that red blood cells (RBCs) may assume, a tear-drop shape. Normally, RBCs are round.
This photomicrograph shows normal red blood cells (RBCs) as seen in the microscope after staining.
Elliptocytosis is a hereditary disorder of the red blood cells (RBCs). In this condition, the RBCs assume an elliptical shape, rather than the typical round shape.
Spherocytosis is a hereditary disorder of the red blood cells (RBCs), which may be associated with a mild anemia. Typically, the affected RBCs are small, spherically shaped, and lack the light centers seen in normal, round RBCs.
Sickle cell anemia is an inherited disorder in which abnormal hemoglobin (the red pigment inside red blood cells) is produced. The abnormal hemoglobin causes red blood cells to assume a sickle shape, like the ones seen in this photomicrograph.
Basophils are a specific type of white blood cell. These cells are readily stained with basic dyes (this is where the name comes from). Note the dark grains inside the cellular fluid (cytoplasm) of this basophil. Basophils make up only a small portion of the number of white blood cells but are important parts of the body's immune response. They release histamine and other chemicals that act on the blood vessels when the immune response is triggered.
Malarial parasites are visible within the red blood cells. They are stained a dark bluish color.
Malaria is a disease caused by parasites. This picture shows dark orange-stained malaria parasites inside red blood cells (a) and outside the cells (b). Note the large cells that look like targets; it is unknown how these target cells are related to this disease.
These crescent or sickle-shaped red blood cells (RBCs) are present with Sickle cell anemia, and stand out clearly against the normal round RBCs. These abnormally shaped cells may become entangled and block blood flow in the small blood vessels (capillaries).
This photomicrograph of red blood cells (RBCs) shows both sickle-shaped and Pappenheimer bodies.
These abnormal red blood cells (RBCs) resemble targets. These cells are seen in association with some forms of anemia, and following the removal of the spleen (splenectomy).
Blood transports oxygen and nutrients to body tissues and returns waste and carbon dioxide. Blood distributes nearly everything that is carried from one area in the body to another place within the body. For example, blood transports hormones from endocrine organs to their target organs and tissues. Blood helps maintain body temperature and normal pH levels in body tissues. The protective functions of blood include clot formation and the prevention of infection.
The complete blood count (CBC) is test, used to diagnose and monitor numerous diseases. It can reflect problems with fluid volume (such as dehydration) or loss of blood. It can show abnormalities in the production, life span, and destruction of blood cells. It can reflect acute or chronic infection, allergies, and problems with clotting. The CBC test identifies and counts the 7 types of cells found in the blood, red blood cell, neutrophil, eosinophil, basophil, lymphocyte, monocyte, and platelet. How the Test is PerformedA blood sample is needed. How to Prepare for the TestThere is no special preparation needed. How the Test will FeelWhen the needle is inserted to draw blood, you may feel moderate pain. Some people feel only a prick or stinging. Afterward there may be some throbbing or slight bruising. This soon goes away. Why the Test is PerformedA CBC is a commonly performed lab test. It can be used to detect or monitor many different health conditions. Your health care provider may order this test:
Normal ResultsBlood counts may vary with altitude. In general, normal results are: RBC count:
WBC count:
Hematocrit:
Hemoglobin:
Red blood cell indices:
Platelet count:
The examples above are common measurements for results of these tests. Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your doctor about the meaning of your specific test results. What Abnormal Results MeanHigh RBC, hemoglobin, or hematocrit may be due to:
Low RBC, hemoglobin, or hematocrit is a sign of anemia, which can result from:
A lower than normal white blood cell count is called leukopenia. A decreased WBC count may be due to:
A high WBC count is called leukocytosis. It can result from:
A high platelet count may be due to:
A low platelet count may be due to:
RisksThere is very little risk involved with having your blood taken. Veins and arteries vary in size from one person to another, and from one side of the body to the other. Taking blood from some people may be more difficult than from others. Other risks associated with having blood drawn are slight, but may include:
ConsiderationsRBCs transport hemoglobin which, in turn, carries oxygen. The amount of oxygen received by body tissues depends on the amount and function of RBCs and hemoglobin. WBCs are mediators of inflammation and the immune response. There are various types of WBCs that normally appear in the blood:
ReferencesLin JC. Approach to anemia in the adult and child. In: Hoffman R, Benz EJ, Silberstein LE, et al, eds. Hematology: Basic Principles and Practice. 7th ed. Philadelphia, PA: Elsevier; 2018:chap 34. Means RT. Approach to the anemias. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 149. Vajpayee N, Graham SS, Bem S. Basic examination of blood and bone marrow. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 22nd ed. St Louis, MO: Elsevier; 2017:chap 30. Version InfoLast reviewed on: 10/16/2020 Reviewed by: Todd Gersten, MD, Hematology/Oncology, Florida Cancer Specialists & Research Institute, Wellington, FL. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team. Does blood type show on lab results?The results of blood typing will determine if a person is type A, B, AB, or O and if he or she is Rh negative or positive. The results will tell the healthcare provider what blood or blood components will be safe for the person to receive.
How do you read your CBC results?When you get your report, you'll see two columns: a “reference range” and your results. If your results are inside the reference range, they're considered normal. If your results are higher or lower than the reference range, they're abnormal.
How do I find out what my blood type is?The best way to learn what blood type you have is by giving a blood sample. You can ask your healthcare professional to check for your blood type during regular blood testing, or you may find out this information when donating blood. There are even at-home test kits you can purchase.
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