CBC blood test

Complete blood count; Anemia - CBC

A complete blood count (CBC) test measures the following:

The number of white blood cells (WBC count)
WBC count
A WBC count is a blood test to measure the number of white blood cells (WBCs) in the blood. It is a part of a complete blood count (CBC). WBCs are a...
Image

Read Article Now Book Mark Article
The number of red blood cells (RBC count)
RBC count
An RBC count is a blood test that measures how many red blood cells (RBCs) you have. RBCs contain hemoglobin, a protein which carries oxygen. How mu...
Image

Read Article Now Book Mark Article
The number of platelets
The total amount of hemoglobin in the blood
Hemoglobin
Hemoglobin is a protein in red blood cells that carries oxygen. The hemoglobin test measures how much hemoglobin is in your blood.
Image

Read Article Now Book Mark Article
The fraction of the blood composed of red blood cells (hematocrit)
Hematocrit
Hematocrit is a blood test that measures how much of a person's blood is made up of red blood cells as opposed to plasma. This measurement depends o...
Image

Read Article Now Book Mark Article

The CBC test also provides information about the following measurements:

Mean red blood cell volume (MCV)
Mean hemoglobin amount per red blood cell (MCH)
Hemoglobin
Hemoglobin is a protein in red blood cells that carries oxygen. The hemoglobin test measures how much hemoglobin is in your blood.
Image

Read Article Now Book Mark Article
The mean amount of hemoglobin relative to the size of the cell (hemoglobin concentration) per red blood cell (MCHC)

How the Test is Performed

A blood sample is needed.

How to Prepare for the Test

There is no special preparation needed.

How the Test will Feel

When 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 Performed

A 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:

If you are having symptoms, such as fatigue, weight loss, fever or other signs of an infection, weakness, bruising, bleeding, or any signs of cancer
When you are receiving treatments (medicines or radiation) that may change your blood count results
To monitor a long-term (chronic) health problem that may change your blood count results, such as chronic kidney disease

Normal Results

Blood counts may vary with altitude. In general, normal results are:

RBC count:

Male: 4.7 to 6.1 million cells/mcL
Female: 4.2 to 5.4 million cells/mcL

WBC count:

4,500 to 10,000 cells/mcL

Hematocrit:

Male: 40.7% to 50.3%
Female: 36.1% to 44.3%

Hemoglobin:

Male: 13.8 to 17.2 gm/dL
Female: 12.1 to 15.1 gm/dL

Red blood cell indices:

MCV: 80 to 95 femtoliter
MCH: 27 to 31 pg/cell
MCHC: 32 to 36 gm/dL

Platelet count:

150,000 to 450,000/dL

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 Mean

High RBC, hemoglobin, or hematocrit may be due to:

A lack of enough water and fluids, such as from severe diarrhea, excessive sweating, or water pills used to treat high blood pressure
Kidney disease with high erythropoietin production
Erythropoietin
The erythropoietin test measures the amount of a hormone called erythropoietin (EPO) in blood. The hormone tells stem cells in the bone marrow to mak...

Read Article Now Book Mark Article
Low oxygen level in the blood for a long time, most often due to heart or lung disease, chronic carbon monoxide exposure, or living at a high altitude
Polycythemia vera
Polycythemia vera
Polycythemia vera (PV) is a bone marrow disease that leads to an abnormal increase in the number of blood cells. The red blood cells are the most af...

Read Article Now Book Mark Article
Smoking
Use of testosterone

Low RBC, hemoglobin, or hematocrit is a sign of anemia, which can result from:

Blood loss (either sudden, or from problems such as heavy menstrual periods over a long time)
Blood loss
Bleeding is the loss of blood. Bleeding may be:Inside the body (internal)Outside the body (external)Bleeding may occur:Inside the body when blood le...
Image

Read Article Now Book Mark Article
Bone marrow failure (for example, from radiation, infection, or tumor)
Breakdown of red blood cells (hemolysis)
Hemolysis
Hemolysis is the breakdown of red blood cells.

Read Article Now Book Mark Article
Cancer and cancer treatment
Certain long-term (chronic) medical conditions, such as chronic kidney disease, ulcerative colitis, or rheumatoid arthritis
Iron deficiency
Leukemia
Long-term infections such as hepatitis
Hepatitis
Hepatitis is swelling and inflammation of the liver.
Image

Read Article Now Book Mark Article
Poor diet and nutrition, causing too little iron, folate, vitamin B12, or vitamin B6
Folate
Folic acid and folate are both terms for a type of B vitamin (vitamin B9). Folate is a B vitamin that occurs naturally in foods such as green leafy v...
Image

Read Article Now Book Mark Article
Vitamin B12
Vitamin B12 is a water-soluble vitamin. Water-soluble vitamins dissolve in water. After the body uses what it needs of these vitamins, leftover amo...
Image

Read Article Now Book Mark Article
Vitamin B6
Vitamin B6 is a water-soluble vitamin. Water-soluble vitamins dissolve in water so the body cannot store them. Leftover amounts of the vitamin leav...
Image

Read Article Now Book Mark Article
Multiple myeloma
Multiple myeloma
Multiple myeloma is a blood cancer that starts in the plasma cells in the bone marrow. Bone marrow is the soft, spongy tissue found inside most bone...
Image

Read Article Now Book Mark Article

A lower than normal white blood cell count is called leukopenia. A decreased WBC count may be due to:

Alcohol abuse and liver damage
Autoimmune diseases (such as systemic lupus erythematosus)
Systemic lupus erythematosus
Systemic lupus erythematosus (SLE) is an autoimmune disease. In this disease, the immune system of the body mistakenly attacks healthy tissue. It c...
Image

Read Article Now Book Mark Article
Bone marrow failure (for example, due to infection, tumor, radiation, or fibrosis)
Chemotherapy medicines used to treat cancer
Disease of the liver or spleen
Enlarged spleen
Infections caused by viruses, such as mono or AIDS
Medicines

A high WBC count is called leukocytosis. It can result from:

Certain medicines, such as corticosteroids
Infections
Diseases such as lupus, rheumatoid arthritis, or allergy
Rheumatoid arthritis
Rheumatoid arthritis (RA) is a disease that leads to inflammation of the joints and surrounding tissues. It is a long-term disease. It can also aff...
Image

Read Article Now Book Mark Article
Allergy
An allergy is an immune response or reaction to substances that are usually not harmful.
Image

Read Article Now Book Mark Article
Leukemia
Severe emotional or physical stress
Tissue damage (such as from burns or a heart attack)

A high platelet count may be due to:

Bleeding
Diseases such as cancer or blood disease
Iron deficiency
Problems with the bone marrow

A low platelet count may be due to:

Disorders where platelets are destroyed
Pregnancy
Enlarged spleen
Bone marrow failure (for example, due to infection, tumor, radiation, or fibrosis)
Chemotherapy medicines used to treat cancer

Risks

There 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:

Excessive bleeding
Fainting or feeling lightheaded
Hematoma (blood accumulating under the skin)
Infection (a slight risk any time the skin is broken)

Considerations

RBCs 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:

Neutrophils (polymorphonuclear leukocytes)
Band cells (slightly immature neutrophils)
T-type lymphocytes (T cells)
B-type lymphocytes (B cells)
Monocytes
Eosinophils
Eosinophils
An absolute eosinophil count is a blood test that measures the number of one type of white blood cells called eosinophils. Eosinophils become active...
Image

Read Article Now Book Mark Article
Basophils

Open References

References

Lin JC, Benz Jr. EJ. Approach to anemia in the adult and child. In: Hoffman R, Benz EJ, Silberstein LE, et al, eds. Hematology: Basic Principles and Practice. 8th ed. Philadelphia, PA: Elsevier; 2023:chap 35.

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. 24th ed. Philadelphia, PA: Elsevier; 2022:chap 31.

Complete blood count - series - Indication
Presentation

<strong>Complete blood count - series - Indication</strong><p>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.</p>

<strong>Procedure</strong><p>A CBC requires a small blood specimen. Blood is drawn from a vein, usually from the inside of the elbow or the back of the hand. To prepare, the skin should be cleaned with alcohol or iodine before the test. The patient should be seated comfortably or reclining. When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. After the blood is drawn, there may be some throbbing. Although the CBC test is very safe, any blood drawing has a slight risk of complication, including oozing of blood from puncture site; fainting or feeling lightheaded; hematoma (blood accumulating under the skin); multiple punctures to locate veins; or infection (a slight risk any time the skin is broken).</p>

<strong>Results, part 1</strong><p>Results; Normal values vary with altitude and sex. What abnormal results may mean; Low numbers of red blood cells may indicate blood loss; anemia (various types); hemorrhage; bone marrow failure (for example, from radiation, toxin, fibrosis, tumor); erythropoietin deficiency (secondary to renal disease); hemolysis (RBC destruction) from transfusion reaction; leukemia; multiple myeloma; malnutrition (nutritional deficiencies of iron, folate, vitamin B12, vitamin B6); or over hydration. Low numbers of white blood cells (leukopenia) may indicate bone marrow failure (for example, due to granuloma (granular tumor), tumor, or fibrosis); presence of cytotoxic substance; collagen-vascular diseases (such as lupus erythematosus); disease of the liver or spleen; or radiation exposure. High numbers of white blood cells (leukocytosis) may indicate infectious diseases; inflammatory disease (such as rheumatoid arthritis or allergy); leukemia; severe emotional or physical stress; or tissue damage (for example, burns). A low hematocrit may indicate anemia (various types); blood loss (hemorrhage); bone marrow failure (for example, due to radiation, toxin, fibrosis, tumor); hemolysis (RBC destruction) related to transfusion reaction; leukemia; malnutrition or specific nutritional deficiency; multiple myeloma; over hydration; or rheumatoid arthritis. A high hematocrit may indicate dehydration; burns; diarrhea; eclampsia; erythrocytosis; polycythemia vera; or shock. Low hemoglobin values may indicate anemia (various types) or blood loss.</p>

<strong>Results, part 2</strong><p>High numbers of red blood cells may indicate cigarette smoking; low oxygen tension in the blood; congenital heart disease; cor pulmonale; pulmonary fibrosis; polycythemia vera; dehydration (such as from severe diarrhea); or emphysema.</p>

Red blood cells, sickle cell - illustration
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.
Red blood cells, sickle cell
illustration
Megaloblastic anemia - view of red blood cells - illustration
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.
Megaloblastic anemia - view of red blood cells
illustration
Red blood cells, tear-drop shape - illustration
This photomicrograph shows one of the abnormal shapes that red blood cells (RBCs) may assume, a tear-drop shape. Normally, RBCs are round.
Red blood cells, tear-drop shape
illustration
Red blood cells - normal - illustration
This photomicrograph shows normal red blood cells (RBCs) as seen in the microscope after staining.
Red blood cells - normal
illustration
Red blood cells - elliptocytosis - illustration
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.
Red blood cells - elliptocytosis
illustration
Red blood cells - spherocytosis - illustration
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.
Red blood cells - spherocytosis
illustration
Red blood cells - multiple sickle cells - illustration
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.
Red blood cells - multiple sickle cells
illustration
Basophil (close-up) - illustration
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.
Basophil (close-up)
illustration
Malaria, microscopic view of cellular parasites - illustration
Malarial parasites are visible within the red blood cells. They are stained a dark bluish color.
Malaria, microscopic view of cellular parasites
illustration
Malaria, photomicrograph of cellular parasites - illustration
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.
Malaria, photomicrograph of cellular parasites
illustration
Red blood cells - sickle cells - illustration
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).
Red blood cells - sickle cells
illustration
Red blood cells - sickle and Pappenheimer - illustration
This photomicrograph of red blood cells (RBCs) shows both sickle-shaped and Pappenheimer bodies.
Red blood cells - sickle and Pappenheimer
illustration
Red blood cells, target cells - illustration
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).
Red blood cells, target cells
illustration
Formed elements of blood - illustration
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.
Formed elements of blood
illustration

Complete blood count - series - Indication
Presentation

Red blood cells, sickle cell - illustration
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.
Red blood cells, sickle cell
illustration
Megaloblastic anemia - view of red blood cells - illustration
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.
Megaloblastic anemia - view of red blood cells
illustration
Red blood cells, tear-drop shape - illustration
This photomicrograph shows one of the abnormal shapes that red blood cells (RBCs) may assume, a tear-drop shape. Normally, RBCs are round.
Red blood cells, tear-drop shape
illustration
Red blood cells - normal - illustration
This photomicrograph shows normal red blood cells (RBCs) as seen in the microscope after staining.
Red blood cells - normal
illustration
Red blood cells - elliptocytosis - illustration
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.
Red blood cells - elliptocytosis
illustration
Red blood cells - spherocytosis - illustration
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.
Red blood cells - spherocytosis
illustration
Red blood cells - multiple sickle cells - illustration
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.
Red blood cells - multiple sickle cells
illustration
Basophil (close-up) - illustration
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.
Basophil (close-up)
illustration
Malaria, microscopic view of cellular parasites - illustration
Malarial parasites are visible within the red blood cells. They are stained a dark bluish color.
Malaria, microscopic view of cellular parasites
illustration
Malaria, photomicrograph of cellular parasites - illustration
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.
Malaria, photomicrograph of cellular parasites
illustration
Red blood cells - sickle cells - illustration
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).
Red blood cells - sickle cells
illustration
Red blood cells - sickle and Pappenheimer - illustration
This photomicrograph of red blood cells (RBCs) shows both sickle-shaped and Pappenheimer bodies.
Red blood cells - sickle and Pappenheimer
illustration
Red blood cells, target cells - illustration
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).
Red blood cells, target cells
illustration
Formed elements of blood - illustration
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.
Formed elements of blood
illustration

A Closer Look

Anemia - InDepth

Talking to your MD

Self Care

Tests for CBC blood test

Review Date: 10/16/2022

Reviewed By: Mark Levin, MD, Hematologist and Oncologist, Monsey, NY. Review provided by VeriMed Healthcare Network. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. No warranty of any kind, either expressed or implied, is made as to the accuracy, reliability, timeliness, or correctness of any translations made by a third-party service of the information provided herein into any other language. © 1997- A.D.A.M., a business unit of Ebix, Inc. Any duplication or distribution of the information contained herein is strictly prohibited.

Health Library

CBC blood test

WBC count

RBC count

Hemoglobin

Hematocrit

Hemoglobin

How the Test is Performed

Blood sample

How to Prepare for the Test

How the Test will Feel

Why the Test is Performed

Normal Results

What Abnormal Results Mean

Erythropoietin

Polycythemia vera

Blood loss

Hemolysis

Hepatitis

Folate

Vitamin B12

Vitamin B6

Multiple myeloma

Systemic lupus erythematosus

Rheumatoid arthritis

Allergy

Risks

Considerations

Immune response

Eosinophils

References

Complete blood count - series - Indication

Red blood cells, sickle cell - illustration

Red blood cells, sickle cell

Megaloblastic anemia - view of red blood cells - illustration

Megaloblastic anemia - view of red blood cells

Red blood cells, tear-drop shape - illustration

Red blood cells, tear-drop shape

Red blood cells - normal - illustration

Red blood cells - normal

Red blood cells - elliptocytosis - illustration

Red blood cells - elliptocytosis

Red blood cells - spherocytosis - illustration

Red blood cells - spherocytosis

Red blood cells - multiple sickle cells - illustration

Red blood cells - multiple sickle cells

Basophil (close-up) - illustration

Basophil (close-up)

Malaria, microscopic view of cellular parasites - illustration

Malaria, microscopic view of cellular parasites

Malaria, photomicrograph of cellular parasites - illustration

Malaria, photomicrograph of cellular parasites

Red blood cells - sickle cells - illustration

Red blood cells - sickle cells

Red blood cells - sickle and Pappenheimer - illustration

Red blood cells - sickle and Pappenheimer

Red blood cells, target cells - illustration

Red blood cells, target cells

Formed elements of blood - illustration

Formed elements of blood