cbc indication

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What is being tested?

The complete blood count (CBC) is a test that evaluates the cells that circulate in blood. Blood consists of three types

of cells suspended in fluid called plasma: white blood cells (WBCs), red blood cells (RBCs), and platelets (!Ts).

They are produced and mature primarily in thebone marrowand, under normal circumstances, are released into the

bloodstream as needed.

" CBC is typically performed usin# an automated instrument that measures various parameters, includin# counts of

the cells that are present in a person$s sample of blood. The results of a CBC can provide information about not only

the number of cell types but also can #ive an indication of the physical characteristics of some of the cells. " standard

CBC includes the followin#:

%valuation of white blood cells:WBC count& may or may not include aWBC differential

%valuation of red blood cells:RBC count,hemo#lobin ('b), hematocrit ('ct)and RBC indices, which

includes mean corpuscular volume (C), mean corpuscular hemo#lobin (C'), mean corpuscular

hemo#lobin concentration (C'C), and sometimes red cell distribution width (R*W). The RBC evaluation may

or may not include reticulocyte count.

%valuation of platelets: platelet count& may or may not include mean platelet volume () and+or platelet

distribution width (*W)

The three types of cells evaluated by the CBC include:

White Blood Cells

There are five different types of WBCs, also called leuocytes, that the body uses to maintain a healthy state and to

fi#ht infections or other causes of in-ury. They areneutrophils,lymphocytes,basophils,eosinophils,and monocytes.

They are present in the blood at relatively stable numbers. These numbers may temporarily shift hi#her or lower

dependin# on what is #oin# on in the body. or instance, an infection can stimulate the body to produce a hi#her

number of neutrophils to fi#ht offbacterialinfection. With aller#ies, there may be an increased number of eosinophils.

"n increased number of lymphocytes may be produced with a viralinfection. /n certain disease states, such

as leuemia, abnormal (immature or mature) white cells rapidly multiply, increasin# the WBC count.

Red Blood Cells

Red blood cells, also called erythrocytes, are produced in the bone marrow and released into the bloodstream as

they mature. They contain hemo#lobin, a protein that transports o0y#en throu#hout the body. The typical lifespan of

an RBC is 123 days& thus the bone marrow must continually produce new RBCs to replace those that a#e and

disinte#rate or are lost throu#h bleedin#. " number of conditions can affect the production of new RBCs and+or their

lifespan, in addition to those conditions that may result in si#nificant bleedin#. The CBC determines the number of

RBCs and amount of hemo#lobin present, the proportion of blood made up of RBCs (hematocrit), and whether the

population of RBCs appears to be normal. RBCs normally are uniform with minimal variations in si4e and shape&

however, si#nificant variations can occur with conditions such as vitamin B12 and folate deficiencies,iron deficiency,

and with a variety of other conditions. /f there are insufficient normal RBCs present, a person is said to

have anemiaand may have symptoms such as fati#ue and weaness. uch less fre5uently, there may be too many
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RBCs in the blood (erythrocytosis orpolycythemia). /n e0treme cases, this can interfere with the flow of blood throu#h

the small veins and arteries.

Platelets

latelets, also called thrombocytes, are special cell fra#ments that play an important role in normal blood clottin#. "

person who does not have enou#h platelets may be at an increased ris of e0cessive bleedin# and bruisin#. TheCBC measures the number and si4e of platelets present.

6i#nificant abnormalities in one or more of the blood cell populations can indicate the presence of one or more

conditions. Typically other tests are performed to help determine the cause of abnormal results. 7ften, this re5uires

visual confirmation by e0aminin# ablood smearunder a microscope. " trained laboratorian can evaluate the

appearance and physical characteristics of the blood cells such as si4e, shape and color, notin# any abnormalities

that may be present. "ny additional information is noted and reported to the doctor. This information #ives the health

practitioner additional clues as to the cause of abnormal CBC results.

How is the sample collected for testing?

" blood sample is obtained by insertin# a needle into a vein in the arm or from a fin#erstic (for children and adults)

or heelstic (for infants).

87T%: /f under#oin# medical tests maes you or someone you care for an0ious, embarrassed, or even difficult to

mana#e, you mi#ht consider readin# one or more of the followin# articles:Copin# with Test ain, *iscomfort, and

"n0iety,Tips on Blood Testin#, Tips to 'elp Children throu#h Their edical Tests,and Tips to 'elp the %lderly

throu#h Their edical Tests.

How is it used?

The complete blood count (CBC) is often used as a broad screenin# test to determine an individual$s #eneral health

status. /t can be used to:

6creen for a wide ran#e of conditions and diseases

'elp dia#nose various conditions, such as anemia,infection, inflammation, bleedin# disorderor leuemia, to

name -ust a few

onitor the condition and+or effectiveness of treatment after a dia#nosis is established

onitor treatment that is nown to affect blood cells, such as chemotherapy or radiation therapy

" CBC is a panel of tests that evaluates the three types of cells that circulate in the blood and includes the followin#:

%valuation of white blood cells, the cells that are part of the body$s defense system a#ainst infections and

cancer and also play a role inaller#iesand inflammation:

o White blood cell (WBC) countis a count of the total number of white blood cells in a person$s

sample of blood.
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o White blood cell differentialmay or may not be included as part of the panel of tests. /t identifies

and counts the number of the various types of white blood cells present. The five types

includeneutrophils,lymphocytes,monocytes,eosinophils,and basophils.

%valuation of red blood cells, the cells that transport o0y#en throu#hout the body:

o Red blood cell (RBC) countis a count of the actual number of red blood cells in a person$s sample

of blood.

o 'emo#lobinmeasures the amount of the o0y#en9carryin# protein in the blood.

o 'ematocritmeasures the percenta#e of a person$s blood that consists of red blood cells.

o Red blood cell indices are calculations that provide information on the physical characteristics of

the RBCs:

ean corpuscular volume (C) is a measurement of the avera#e si4e of RBCs.

ean corpuscular hemo#lobin (C') is a calculation of the avera#e amount of o0y#en9

carryin# hemo#lobin inside a red blood cell.

ean corpuscular hemo#lobin concentration (C'C) is a calculation of the avera#e

percenta#e of hemo#lobin inside a red cell.

Red cell distribution width (R*W), which may be included in a CBC, is a calculation of the

variation in the si4e of RBCs.

o The CBC may also include reticulocyte count, which is a measurement of the absolute count or

percenta#e of youn# red blood cells in blood.

%valuation of platelets, cell fra#ments that are vital for normal blood clottin#:

o The platelet countis the number of platelets in a person$s sample of blood.

o ean platelet volume () may be reported with a CBC. /t is a calculation of the avera#e si4e of

platelets.

o latelet distribution width (*W) may also be reported with a CBC. /t is a measurement of the

variation of platelet si4e.

When is it ordered?

The CBC is a very common test. any people have a CBC performed when they have a routine health e0amination.

/f a person is healthy and has results that are within normal limits, then he or she may not re5uire another CBC until

their health status chan#es or until their doctor feels that it is necessary.

" CBC may be ordered when a person has any number of si#nsand symptomsthat may be related to disorders that

affect blood cells. When an individual has fati#ue or weaness or has an infection, inflammation, bruisin#, or

bleedin#, a doctor may order a CBC to help dia#nose the cause and+or determine its severity.
http://labtestsonline.org/understanding/analytes/differential/http://labtestsonline.org/understanding/analytes/differential/http://labtestsonline.org/glossary/neutrophil/http://labtestsonline.org/glossary/neutrophil/http://labtestsonline.org/glossary/neutrophil/http://labtestsonline.org/glossary/lymphocyte/http://labtestsonline.org/glossary/lymphocyte/http://labtestsonline.org/glossary/lymphocyte/http://labtestsonline.org/glossary/monocyte/http://labtestsonline.org/glossary/monocyte/http://labtestsonline.org/glossary/eosinophil/http://labtestsonline.org/glossary/eosinophil/http://labtestsonline.org/glossary/eosinophil/http://labtestsonline.org/glossary/basophil/http://labtestsonline.org/understanding/analytes/rbc/http://labtestsonline.org/understanding/analytes/hemoglobin/http://labtestsonline.org/understanding/analytes/hematocrit/http://labtestsonline.org/understanding/analytes/hematocrit/http://labtestsonline.org/understanding/analytes/reticulocyte/http://labtestsonline.org/understanding/analytes/platelet/http://labtestsonline.org/understanding/analytes/platelet/http://labtestsonline.org/glossary/sign/http://labtestsonline.org/glossary/symptom/http://labtestsonline.org/glossary/infection/http://labtestsonline.org/glossary/inflammation/http://labtestsonline.org/understanding/analytes/differential/http://labtestsonline.org/glossary/neutrophil/http://labtestsonline.org/glossary/lymphocyte/http://labtestsonline.org/glossary/monocyte/http://labtestsonline.org/glossary/eosinophil/http://labtestsonline.org/glossary/basophil/http://labtestsonline.org/understanding/analytes/rbc/http://labtestsonline.org/understanding/analytes/hemoglobin/http://labtestsonline.org/understanding/analytes/hematocrit/http://labtestsonline.org/understanding/analytes/reticulocyte/http://labtestsonline.org/understanding/analytes/platelet/http://labtestsonline.org/glossary/sign/http://labtestsonline.org/glossary/symptom/http://labtestsonline.org/glossary/infection/http://labtestsonline.org/glossary/inflammation/


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When a person has been dia#nosed with a disease nown to affect blood cells, a CBC will often be ordered on a

re#ular basis to monitor their condition. !iewise, if someone is receivin# treatment for a blood9related disorder, then

a CBC may be performed fre5uently to determine if the treatment is effective.

6ome therapies, such as chemotherapy, can affectbone marrowproduction of cells. 6ome medications can

decreaseWBC countsoverall. " CBC may be ordered on a re#ular basis to monitor these dru# treatments.

Bac to top

What does the test result mean?

" health practitioner typically evaluates and interprets results from the components of the CBC to#ether. *ependin#

on the purpose of the test, a number of additional or follow9up tests may be ordered for further investi#ation.

The followin# tables briefly and #enerally e0plain what the result for each component of the CBC may mean.

WBC evaluation

RBC evaluation

latelet evaluation

For detailed information on each test component, click on the name of the component to go to the specific article.

Components of the CBC

WBC Evaluation

TEST FULL NAME

EXAMPLES OF CAUSES OF A LOW

COUNT

EXAMPLES OF CAUSES OF A HIGH

COUNT

WBC White Blood Cell Count ;nown as leuopenia

Bone marrow

disordersor dama#e

"utoimmune conditions

6evere infections

(sepsis)

!ymphomaor other

cancer that spread to

thebone marrow

*iseases of immune

system (e.#.,'/)

;nown as leuocytosis

/nfection, most

commonly bacterialor viral

/nflammation

!euemia, myeloproliferative

disorders

"ller#ies,asthma

Tissue death (trauma,

burns, heart attac)

/ntense e0ercise or severe

stress
http://labtestsonline.org/glossary/bone-marrow/http://labtestsonline.org/glossary/bone-marrow/http://labtestsonline.org/understanding/analytes/wbc/http://labtestsonline.org/understanding/analytes/cbc/tab/test#tophttp://labtestsonline.org/understanding/analytes/cbc/tab/test#wbchttp://labtestsonline.org/understanding/analytes/cbc/tab/test#rbchttp://labtestsonline.org/understanding/analytes/cbc/tab/test#plthttp://labtestsonline.org/understanding/analytes/wbchttp://labtestsonline.org/understanding/conditions/bone-marrow-disorders/http://labtestsonline.org/understanding/conditions/bone-marrow-disorders/http://labtestsonline.org/understanding/conditions/bone-marrow-disorders/http://labtestsonline.org/understanding/conditions/autoimmune/http://labtestsonline.org/understanding/conditions/sepsis/http://labtestsonline.org/understanding/conditions/lymphoma/http://labtestsonline.org/glossary/bone-marrow/http://labtestsonline.org/glossary/bone-marrow/http://labtestsonline.org/understanding/conditions/hiv/http://labtestsonline.org/understanding/conditions/hiv/http://labtestsonline.org/glossary/infection/http://labtestsonline.org/glossary/bacterium/http://labtestsonline.org/glossary/virus/http://labtestsonline.org/glossary/inflammation/http://labtestsonline.org/understanding/conditions/leukemia/http://labtestsonline.org/understanding/conditions/myelopro-disorders/http://labtestsonline.org/understanding/conditions/myelopro-disorders/http://labtestsonline.org/understanding/conditions/allergies/http://labtestsonline.org/understanding/conditions/asthma/http://labtestsonline.org/understanding/conditions/asthma/http://labtestsonline.org/understanding/conditions/heart-attack/http://labtestsonline.org/glossary/bone-marrow/http://labtestsonline.org/understanding/analytes/wbc/http://labtestsonline.org/understanding/analytes/cbc/tab/test#tophttp://labtestsonline.org/understanding/analytes/cbc/tab/test#wbchttp://labtestsonline.org/understanding/analytes/cbc/tab/test#rbchttp://labtestsonline.org/understanding/analytes/cbc/tab/test#plthttp://labtestsonline.org/understanding/analytes/wbchttp://labtestsonline.org/understanding/conditions/bone-marrow-disorders/http://labtestsonline.org/understanding/conditions/bone-marrow-disorders/http://labtestsonline.org/understanding/conditions/autoimmune/http://labtestsonline.org/understanding/conditions/sepsis/http://labtestsonline.org/understanding/conditions/lymphoma/http://labtestsonline.org/glossary/bone-marrow/http://labtestsonline.org/understanding/conditions/hiv/http://labtestsonline.org/glossary/infection/http://labtestsonline.org/glossary/bacterium/http://labtestsonline.org/glossary/virus/http://labtestsonline.org/glossary/inflammation/http://labtestsonline.org/understanding/conditions/leukemia/http://labtestsonline.org/understanding/conditions/myelopro-disorders/http://labtestsonline.org/understanding/conditions/myelopro-disorders/http://labtestsonline.org/understanding/conditions/allergies/http://labtestsonline.org/understanding/conditions/asthma/http://labtestsonline.org/understanding/conditions/heart-attack/


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TEST FULL NAME

EXAMPLES OF CAUSES OF A LOW

COUNT

EXAMPLES OF CAUSES OF A HIGH

COUNT

*iffWhite Blood Cell *ifferential

(8ot always performed& maybe done as part of or in follow

up to CBC)

8eu,

8,

polys

"bsolute neutrophilcount,

cbc indication

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