Complete Blood Count (CBC)

CBC (Complete Blood Count)

Results

A complete blood count (CBC) gives important information about the kinds and numbers of cells in the blood, especially red blood cells , white blood cells , and platelets. A CBC helps your health professional check any symptoms, such as weakness, fatigue, or bruising, you may have. A CBC also helps him or her diagnose conditions, such as anemia, infection, and many other disorders.

Normal

Normal values can vary from lab to lab.

Normal values for the complete blood count (CBC) tests depend on age, sex, how high above sea level you live, and the type of blood sample. Your health professional may use all the CBC values to check for a condition. For example, the red blood cell (RBC) count, hemoglobin (Hgb), and hematocrit (HCT) are the most important values needed to tell whether a person has anemia, but the red blood cell indices and the blood smear also help with the diagnosis and may show a possible cause for the anemia.

To see if the white blood cell (WBC, leukocyte) count is good and how the cells look on the smear, your health professional will look at both the number (WBC count) and the WBC differential. To see whether there are too many or too few of a certain type of cell, your health professional will look at the total count and the percentage of that particular cell. There are normal values for the total number of each type of white cell.

Pregnancy can change these blood values. Your doctor will talk with you about normal values during each trimester of your pregnancy.

White blood cell (WBC, leukocyte) count

Men and nonpregnant women:	4,500–11,000/mcL3 or 4.5–11.0 x 109/liter (SI units)
Pregnant women:	1st trimester: 6,600–14,100/mcL or 6.6–14.1 x 109/L 2nd trimester: 6,900–17,100/mcL or 6.9–17.1 x 109/L 3rd trimester: 5,900–14,700/mcL or 5.9–14.7 x 109/L Postpartum: 9,700–25,700/mcL or 9.7–25.7 x 109/L

 

White blood cell types (WBC differential)

Neutrophils:	50%–62%
Band neutrophils:	3%–6%
Lymphocytes:	25%–40%
Monocytes:	3%–7%
Eosinophils:	0%–3%
Basophils:	0%–1%

 

Red blood cell (RBC) count

Men:	4.7–6.1 million RBCs per microliter (mcL) or 4.7–6.1 x 1012/liter (SI units)
Women:	4.2–5.4 million RBCs per mcL or 4.2–5.4 x 1012/L
Children:	4.0–5.5 million RBCs per mcL or 4.6–4.8 x 1012/L
Newborn:	4.8–7.1 million RBCs per mcL or 4.8–7.1 x 1012/L

 

Hematocrit (HCT)

Men:	42%–52% or 0.42–0.52 volume fraction (SI units)
Women:	37%–47% or 0.37–0.47 volume fraction
Pregnant women:	1st trimester: 35%–46% 2nd trimester: 30%–42% 3rd trimester: 34%–44% Postpartum: 30%–44%
Children:	32%–44%
Newborns:	44%–64%

 

Hemoglobin (Hgb)

Men:	14–18 grams per deciliter (g/dL) or 8.7–11.2 millimoles per liter (mmol/L) (SI units)
Women:	12–16 g/dL or 7.4–9.9 mmol/L
Pregnant women:	1st trimester: 11.4–15.0 g/dL or 7.1–9.3 mmol/L 2nd trimester: 10.0–14.3 g/dL or 6.2–8.9 mmol/L 3rd trimester: 10.2–14.4 g/dL or 6.3–8.9 mmol/L Postpartum: 10.4–18.0 g/dL or 6.4–9.3 mmol/L
Children:	9.5–15.5 g/dL
Newborn:	14–24 g/dL

In general, a normal hemoglobin level is about one-third the value of the hematocrit.

 

Red blood cell indices

Mean corpuscular volume (MCV):	82–98 femtoliters (fL)
Mean corpuscular hemoglobin (MCH):	26–34 picograms (pg)
Mean corpuscular hemoglobin concentration (MCHC):	31–38 grams per deciliter (g/dL) or 31%–38%

 

Red cell distribution width (RDW)

Normal:	11.5%–14.6%

 

Platelet (thrombocyte) count

Normal:	Children: 150,000–450,000 platelets per mm 3 or 150–450 x 109/liter (SI units) Adults: 150,000–400,000 platelets per mm3 or 150–400 x 109/liter (SI units)

 

Mean platelet volume (MPV)

Normal:	Children: 7.4–10.4 mcm3 or 7.4–10.4 fL Adults: 7.4–10.4 mcm3 or 7.4–10.4 fL

 

Blood smear

Normal:	Blood cells are normal in shape, size, color, and number.

 

High values

Red blood cell (RBC)

• Conditions that cause high RBC values include smoking, exposure to carbon monoxide, long-term lung disease, kidney disease, some cancers, certain forms of heart disease, alcoholism, liver disease, a rare disorder of the bone marrow (polycythemia vera), or a rare disorder of hemoglobin that binds oxygen tightly.
• Conditions that affect the body's water content can also cause high RBC values. These conditions include dehydration, diarrhea or vomiting, excessive sweating, severe burns, and the use of diuretics. The lack of fluid in the body makes the RBC volume look high; this is sometimes called spurious polycythemia.

White blood cell (WBC, leukocyte)

• Conditions that cause high WBC values include infection, inflammation, damage to body tissues (such as a heart attack), severe physical or emotional stress (such as a fever, injury, or surgery), burns, kidney failure, lupus, tuberculosis (TB), rheumatoid arthritis, malnutrition, leukemia, and diseases such as cancer.
• The use of corticosteroids, underactive adrenal glands, thyroid gland problems, certain medicines, or removal of the spleen can also cause high WBC values.

Platelets

• High platelet values may be seen with bleeding, iron deficiency, some diseases like cancer, or problems with the bone marrow.

Low values

Red blood cell (RBC)

• Anemia lowers RBC values. Anemia can be caused by heavy menstrual bleeding, stomach ulcers, colon cancer, inflammatory bowel disease, some tumors, Addison's disease, thalassemia, lead poisoning, sickle cell disease, or reactions to some chemicals and medicines. A low RBC value may also be seen if the spleen has been taken out.
• A lack of folic acid or vitamin B12 can also cause anemia, such as pernicious anemia, which is a problem with absorbing vitamin B12.
• The RBC indices value and a blood smear may help find the cause of anemia.

White blood cell (WBC, leukocyte)

• Conditions that can lower WBC values include chemotherapy and reactions to other medicines, aplastic anemia, viral infections, malaria, alcoholism, AIDS, lupus, or Cushing's syndrome.
• A large spleen can lower the WBC count.

Platelets

• Low platelet values can occur in pregnancy or idiopathic thrombocytopenic purpura (ITP) and other conditions that affect how platelets are made or that destroy platelets.
• A large spleen can lower the platelet count.

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Author:	Caroline Rea, RN, BS, MS	Last Updated: September 12, 2008
Medical Review:	Anne C. Poinier, MD - Internal Medicine Joseph O'Donnell, MD - Hematology/Oncology
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