Complete blood count CBC - Mayo Clinic

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Complete blood count CBC

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Overview

A complete blood count (CBC) is a blood test used to evaluate your overall health and detect a wide range of disorders, including anemia, infection and leukemia. A complete blood count test measures several components and features of your blood, including: Red blood cells, which carry oxygen White blood cells, which fight infection Hemoglobin, the oxygen-carrying protein in red blood cells Hematocrit, the proportion of red blood cells to the fluid component, or plasma, in your blood Platelets, which help with blood clotting Abnormal increases or decreases in cell counts as revealed in a complete blood count may indicate that you have an underlying medical condition that calls for further evaluation.

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Why it s done

A complete blood count is a common blood test that's done for a variety of reasons: To review your overall health. Your doctor may recommend a complete blood count as part of a routine medical examination to monitor your general health and to screen for a variety of disorders, such as anemia or leukemia. To diagnose a medical condition. Your doctor may suggest a complete blood count if you're experiencing weakness, fatigue, fever, inflammation, bruising or bleeding. A complete blood count may help diagnose the cause of these signs and symptoms. If your doctor suspects you have an infection, the test can also help confirm that diagnosis. To monitor a medical condition. If you've been diagnosed with a blood disorder that affects blood cell counts, your doctor may use complete blood counts to monitor your condition. To monitor medical treatment. A complete blood count may be used to monitor your health if you're taking medications that may affect blood cell counts.

More Information

AnemiaAnorexia nervosaAntisocial personality disorderAtaxiaAtypical depressionBreast cancerBurning mouth syndromeChronic lymphocytic leukemiaChronic myelogenous leukemiaColon cancerCyclothymia (cyclothymic disorder)DementiaDepression (major depressive disorder)Enlarged spleen (splenomegaly)Essential thrombocythemiaFibromyalgiaGilbert syndromeHairy cell leukemiaHeart diseaseHigh blood pressure in childrenIllness anxiety disorderImmune thrombocytopenia (ITP)Kawasaki diseaseLupusMedian arcuate ligament syndrome (MALS)Multiple myelomaMyelodysplastic syndromesMyelofibrosisPersonality disordersPolycythemia veraPorphyriaPost-vasectomy pain syndromeSexually transmitted diseases (STDs)Swollen lymph nodesTetralogy of FallotThalassemiaThrombocytosisTonsillitisUterine fibroidsVitiligoShow more related information Request an Appointment at Mayo Clinic There is a problem with information submitted for this request. Review/update the information highlighted below and resubmit the form.

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How you prepare

If your blood sample is being tested only for a complete blood count, you can eat and drink normally before the test. If your blood sample will be used for additional tests, you may need to fast for a certain amount of time before the test. Your doctor will give you specific instructions.

What you can expect

For a complete blood count, a member of your health care team takes a sample of blood by inserting a needle into a vein in your arm, usually at the bend in your elbow. The blood sample is sent to a lab for analysis. You can return to your usual activities immediately.

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. By Mayo Clinic Staff Request an Appointment at Mayo Clinic Dec. 22, 2020 Print Share on: FacebookTwitter Show references Complete blood count. Lab Tests Online. https://labtestsonline.org/understanding/analytes/cbc/tab/test. Accessed Aug. 29, 2016. CBC with differential, blood. Mayo Medical Laboratories. http://www.mayomedicallaboratories.com/test-catalog/Clinical+and+Interpretive/9109. Accessed Aug. 29, 2016. Understanding blood counts. Leukemia and Lymphoma Society. http://www.lls.org/managingyourcancer/labandimagingtests/understandingbloodcounts. Accessed Aug. 29, 2016.

Related

Anemia Anorexia nervosa Antisocial personality disorder Ataxia Atypical depression Blood Basics Breast cancer Burning mouth syndrome Cancer Chronic lymphocytic leukemia Chronic myelogenous leukemia Colon cancer Cyclothymia (cyclothymic disorder) Dementia Depression (major depressive disorder) Enlarged spleen (splenomegaly) Essential thrombocythemia Fibromyalgia Gilbert syndrome Hairy cell leukemia Heart disease High blood pressure in children Illness anxiety disorder Immune thrombocytopenia (ITP) Kawasaki disease Lupus Median arcuate ligament syndrome (MALS) Microcephaly Monoclonal gammopathy of undetermined significance (MGUS) Multiple myeloma Myelodysplastic syndromes Myelofibrosis Personality disorders Polycythemia vera Porphyria Post-vasectomy pain syndrome Sexually transmitted diseases (STDs) Swollen lymph nodes Tetralogy of Fallot Thalassemia Thrombocytosis Tonsillitis Uterine fibroids Vitiligo Show more related content

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Complete blood count CBC

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