Complete Blood Count (CBC)

Introduction:

A complete blood count (CBC), also known as a complete blood cell count, full blood count (FBC), or full blood exam (FBE).
CBC is a blood panel that gives information about the cells that circulate in the bloodstream
– white blood cells (leukocytes)
– red blood cells (erythrocytes) and
– platelets (thrombocytes)

 

Importance:

CBC is done to monitor overall health, to screen for some diseases, to confirm a diagnosis of some medical conditions, to monitor a medical condition, and to monitor changes in the body caused by medical treatments.
 This common blood test measures the amount of various types of blood cells in a sample of your blood. Blood cancers may be detected using this test if too many or too few of a type of blood cell or abnormal cells are found. A bone marrow biopsy may help confirm a diagnosis of a blood cancer.
 Abnormally high or low counts may indicate the presence of many forms of disease, and hence blood counts are amongst the most commonly performed blood tests in medicine, as they can provide an overview of a patient's general health status.

Components of CBC:

A complete blood counts includes:

1. White cells: All the white cell types are given as a percentage and as an absolute number per litre. A high WBC may indicate an infection.

2. Red cells: Iron deficiency anemia shows up as a low RBC count.

3. Hemoglobin: A low level of hemoglobin is a sign of anemia.

4. Hematocrit (Hct) or packed cell volume (PCV): This is the fraction of whole blood volume that consists of red blood cells.

5. Platelet numbers are given, as well as information about their size and the range of sizes in the blood.

6. Mean platelet volume (MPV): a measurement of the average size of platelets. 

7. Red blood cell indices

A. Mean corpuscular volume (MCV) is the average size of a RBC and is calculated by dividing Hct by the RBC count.

B. Mean corpuscular hemoglobin (MCH): the average amount of hemoglobin per RBC

C. Mean corpuscular hemoglobin concentration (MCHC): the average concentration of hemoglobin in the cells.

D. Red blood cell distribution width (RDW): the variation in cellular volume of the RBC population.

Mean corpuscular volume (MCV) relation with Anemia types and other disease conditions:

Anemia is classified as microcytic or macrocytic if the MCV value is above or below the expected normal range; anemias are classified as normocytic if the MCV is within the expected range. Other conditions that can affect MCV include thalassemia, reticulocytosis, alcoholism, chemotherapy, Vitamin B12 deficiency, and/or folic acid deficiency.

CBC with WBC Differential:

 1. Neutrophil granulocytes:

– May indicate bacterial infection.
– May also be raised in acute viral infections.

2. Lymphocytes:

– Higher with some viral infections such as glandular fever
– Raised in chronic lymphocytic leukemia (CLL)
– Can be decreased in HIV infection.
– In adults, lymphocytes are the second most common WBC type after neutrophils.
– In young children under age 8, lymphocytes are more common than neutrophils.

3.  Monocytes:

– May be raised in bacterial infection, tuberculosis, malaria, Rocky Mountain spotted fever,
monocytic leukemia, chronic ulcerative colitis and regional enteritis

4.  Eosinophil granulocytes:

– Increased in parasitic infections, asthma, or allergic reaction.

5.  Basophil granulocytes:

– May be increased in bone marrow related conditions such as leukemia or lymphoma

Normal Range of Diffrent components of CBC:

Refrences:
1. http://www.emedicinehealth.com/complete_blood_count_cbc/page2_em.htm
2. www.mayoclinic.org/tests-procedures/complete-blood-count/home/ovc-20257165
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American Association of Blood Banks (24 April 2014), "Five Things Physicians and Patients Should Question", Choosing Wisely: an initiative of the ABIM Foundation, American Association of Blood Banks, retrieved 25 July 2014, which cites
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7. Buttarello, M; Plebani, M (Jul 2008). "Automated blood cell counts: state of the art.". American journal of clinical pathology. 130 (1): 104–16. PMID 18550479. doi:10.1309/EK3C7CTDKNVPXVTN.
David C., Dugdale (19 March 2012). "CBC: MedlinePlus Medical Encyclopedia". MedlinePlus. United States National Library of Medicine. Retrieved 29 July 2014.
8."Complete Blood count with Differential". RbCeus.com. 2013. Retrieved 2014-11-21.
"RBC indices". MedlinePlus: U.S. National Library of Medicine. Retrieved 1 June 2013.
References at Reference ranges for blood tests#White blood cells 2
9. https://en.wikipedia.org/wiki/Complete_blood_count