Tests and Procedures

Complete blood count (CBC)

Overview Why it's done How you prepare What you can expect Results

Results

The following are normal complete blood count results for adults:

Red blood cell count

Male: 4.35-5.65 trillion cells/L*
(4.35-5.65 million cells/mcL**)

Female: 3.92-5.13 trillion cells/L
(3.92-5.13 million cells/mcL)
Hemoglobin

Male: 13.2-16.6 grams/dL***
(132-166 grams/L)

Female: 11.6-15 grams/dL
(116-150 grams/L)
Hematocrit

Male: 38.3-48.6 percent

Female: 35.5-44.9 percent
White blood cell count

3.4-9.6 billion cells/L
(3,400 to 9,600 cells/mcL)
Platelet count

Male: 135-317 billion/L
(135,000 to 317,000/mcL)

Female: 157-371 billion/L
(157,000 to 371,000/mcL)
  • * L = liter
  • ** mcL = microliter
  • *** dL = deciliter

Not a definitive test

A complete blood count is typically not a definitive diagnostic test. Depending on the reason your doctor recommended this test, results outside the normal range may or may not require follow-up. Your doctor may need to look at the results of a CBC along with results of other blood tests, or additional tests may be necessary.

For example, if you're otherwise healthy and have no signs or symptoms of illness, results slightly outside the normal range on a complete blood count may not be a cause for concern, and follow-up may not be needed. Of if you're undergoing cancer treatment, the results of a complete blood count outside the normal range may indicate a need to alter your treatment plan.

In some cases, if your results are significantly above or below the normal ranges, your doctor may refer you to a doctor who specializes in blood disorders (hematologist).

What the results may indicate

Results in the following areas above or below the normal ranges on a complete blood count may indicate a problem.

  • Red blood cell count, hemoglobin and hematocrit. The results of your red blood cell count, hemoglobin and hematocrit are related because they each measure aspects of your red blood cells.

    If the measures in these three areas are lower than normal, you have anemia. Anemia causes fatigue and weakness. Anemia has many causes, including low levels of certain vitamins or iron, blood loss, or an underlying condition.

    A red blood cell count that's higher than normal (erythrocytosis), or high hemoglobin or hematocrit levels, could point to an underlying medical condition, such as polycythemia vera or heart disease.

  • White blood cell count. A low white blood cell count (leukopenia) may be caused by a medical condition, such as an autoimmune disorder that destroys white blood cells, bone marrow problems or cancer. Certain medications also can cause white blood cell counts to drop.

    If your white blood cell count is higher than normal, you may have an infection or inflammation. Or, it could indicate that you have an immune system disorder or a bone marrow disease. A high white blood cell count can also be a reaction to medication.

  • Platelet count. A platelet count that's lower than normal (thrombocytopenia) or higher than normal (thrombocytosis) is often a sign of an underlying medical condition, or it may be a side effect from medication. If your platelet count is outside the normal range, you'll likely need additional tests to diagnose the cause.

For specifics about what your complete blood count results mean if they fall outside the normal ranges, talk to your doctor.

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