Complete blood count

A complete blood count (CBC), also known as a full blood count (FBC) or full haemogram (FHG), is a set of <a href="/facts/Medical_laboratory/ov10GjQD">medical laboratory</a> tests that provide <a href="/facts/Cytometry/ccN2U17H">information about the cells</a> in a person's <a href="/facts/Blood/03zEulkj">blood</a>. The CBC indicates the counts of <a href="/facts/White_blood_cells/vsDunUK0">white blood cells</a>, <a href="/facts/Red_blood_cells/Kggpq8Jh">red blood cells</a> and <a href="/facts/Platelets/I0xrDVGa">platelets</a>, the concentration of <a href="/facts/Hemoglobin/RsD1MzYA">hemoglobin</a>, and the <a href="/facts/Hematocrit/wg1UalUh">hematocrit</a> (the volume percentage of red blood cells). The <a href="/facts/Red_blood_cell_indices/6geLm4Rw">red blood cell indices</a>, which indicate the average size and hemoglobin content of red blood cells, are also reported, and a <a href="/facts/White_blood_cell_differential/h2dYUtmb">white blood cell differential</a>, which counts the different types of white blood cells, may be included.
The CBC is often carried out as part of a medical assessment and can be used to monitor health or diagnose diseases. The results are interpreted by comparing them to <a href="/facts/Reference_ranges_for_blood_tests/Fls5Gbtb">reference ranges</a>, which vary with sex and age. Conditions like <a href="/facts/Anemia/AgEPPmg8">anemia</a> and <a href="/facts/Thrombocytopenia/qMy4o0Rz">thrombocytopenia</a> are defined by abnormal complete blood count results. The red blood cell indices can provide information about the cause of a person's anemia such as <a href="/facts/Iron-deficiency_anemia/LK17js79">iron deficiency</a> and <a href="/facts/Vitamin_B12_deficiency_anemia/6WVBYjso">vitamin B12 deficiency</a>, and the results of the white blood cell differential can help to diagnose <a href="/facts/Viral_infection/F1Tth6qP">viral</a>, <a href="/facts/Bacterial_infection/X5QcVN5j">bacterial</a> and <a href="/facts/Parasitic_infection/DU94HYrL">parasitic infections</a> and <a href="/facts/Blood_disorder/QB4CeNEF">blood disorders</a> like <a href="/facts/Leukemia/WpEfW0Qh">leukemia</a>. Not all results falling outside of the reference range require medical intervention.
The CBC is usually performed by an <a href="/facts/Hematology_analyzer/qdPbmXUK">automated hematology analyzer</a>, which <a href="/facts/Cell_counting/o6gxP6QL">counts cells</a> and collects information on their size and structure. The concentration of hemoglobin is measured, and the red blood cell indices are calculated from measurements of red blood cells and hemoglobin. Manual tests can be used to independently confirm abnormal results. Approximately 10–25% of samples require a manual <a href="/facts/Blood_smear/ao2R0t11">blood smear</a> review, in which the blood is <a href="/facts/Romanowsky_stain/WWEu7Eu6">stained</a> and viewed under a <a href="/facts/Microscope/ldJp0CI3">microscope</a> to verify that the analyzer results are consistent with the appearance of the cells and to look for abnormalities. The hematocrit can be determined manually by <a href="/facts/Centrifuge/EVGu5ndv">centrifuging</a> the sample and measuring the proportion of red blood cells, and in laboratories without access to automated instruments, blood cells are counted under the microscope using a <a href="/facts/Hemocytometer/5ScMd7yF">hemocytometer</a>.
In 1852, <a href="/facts/Karl_Vierordt/UVBQ9uUj">Karl Vierordt</a> published the first procedure for performing a blood count, which involved spreading a known volume of blood on a microscope slide and counting every cell. The invention of the hemocytometer in 1874 by <a href="/facts/Louis-Charles_Malassez/FypuzalU">Louis-Charles Malassez</a> simplified the microscopic analysis of blood cells, and in the late 19th century, <a href="/facts/Paul_Ehrlich/6XM57Clc">Paul Ehrlich</a> and <a href="/facts/Dmitri_Leonidovich_Romanowsky/0EJz8mEm">Dmitri Leonidovich Romanowsky</a> developed techniques for staining white and red blood cells that are still used to examine blood smears. Automated methods for measuring hemoglobin were developed in the 1920s, and <a href="/facts/Maxwell_Wintrobe/eAQvtsH0">Maxwell Wintrobe</a> introduced the Wintrobe hematocrit method in 1929, which in turn allowed him to define the red blood cell indices. A landmark in the automation of blood cell counts was the <a href="/facts/Coulter_principle/VzbT0Cft">Coulter principle</a>, which was patented by <a href="/facts/Wallace_H._Coulter/zkaUoAe1">Wallace H. Coulter</a> in 1953. The Coulter principle uses <a href="/facts/Electrical_impedance/I06NSXtN">electrical impedance</a> measurements to count blood cells and determine their sizes; it is a technology that remains in use in many automated analyzers. Further research in the 1970s involved the use of <a href="/facts/Optics/p0vq4S1T">optical</a> measurements to count and identify cells, which enabled the automation of the white blood cell differential.

Complete blood count open-in-new

Complete blood count