Cbc (complete blood count)

A complete blood count (CBC) is a blood test that gives important information about your blood cells, especially red blood cells, white blood cells, and platelets.

Each lab has a different range for what's normal. Your lab report should show the range that your lab uses for each test. The normal range is just a guide. Your doctor will also look at your results based on your age, health, and other factors. A value that isn't in the normal range may still be normal for you.

Normal values for the complete blood count (CBC) tests depend on age, sex, and how high above sea level you live. Your doctor 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 doctor 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 doctor 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.

Red blood cells (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, liver disease, and rare disorders such as polycythemia vera (a bone marrow disorder).
• Conditions that affect the body's water content can also cause high RBC values. These conditions includedehydration, diarrhea or vomiting, excessive sweating, and the use ofdiuretics. The lack of fluid in the body makes the RBC volume look high. This is sometimes called secondary polycythemia.

White blood cells (WBC, leukocytes).

• Conditions that cause high WBC values include infection, inflammation, damage to body tissues (such as aheart attack), severe physical or emotional stress (such as a fever, injury, or surgery),tuberculosis (TB),leukemia, and diseases such as cancer.
• The use ofcorticosteroids,thyroid glandproblems, certain medicines, and removal of thespleencan also cause high WBC values.

Platelets.

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

Red blood cells (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, and 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 aspernicious anemia. This is a problem with absorbing vitamin B12.
• Low RBC values and an abnormal blood smear may help find the cause of anemia. An abnormal blood smear would mean blood cells are not normal in shape, size, color, and number.

White blood cells (WBC, leukocytes).

• Conditions that can lower WBC values includechemotherapyand reactions to other medicines,aplastic anemia, viral infections,malaria, alcohol use disorder,AIDS, andlupus.
• A large spleen can lower the WBC count.

Platelets.

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