Complete Blood Count : Procedure, Results


Today in this blog, we learn about Complete blood count (CBC). It is also known as Full blood count (FBC). This report gives us information regarding 

complete blood count report
cbc report
  • Red blood cell (RBC) – which carry O2
  • Haemoglobin – O2 carrying protein in red cell
  • White blood cell (WBC) – which fights with disease
  • Platelet – which help in blood clotting

In 1950s, these cells RBC, WBC, platelet was checked in laboratory under microscope. After that series of invention made & in 1973 George and groner develop light scattering in flow cytometry.

Why to do CBC report?

This is most common blood report done now a days. Millions of CBC test done on everyday basis.

Complete Blood Count report is useful to check

  • general health condition
  • it give clues in wide range of disease conditions like bacterial, viral, parasitic infections, anaemia, blood cancer & many others.

This is inexpensive but most valuable blood report because it suggest what to do next. Just look at the details shown in image of CBC report. Either decrease or increase in reference value in report suggest some abnormalities. I will try my best to explain you, how to interpret the CBC report.

Reference value may be slight differ from laboratory to laboratory. Because it depends on which source they are following. 

Complete Blood Count Test Procedure


complete blood count

It is very simple blood test, in which no advance preparation needed. Lab technician will bind torniquet belt above elbow joint, so he can see vein better. He will take blood & put it into EDTA bulb. The CBC analyzer will interpret blood counts from that sample. It is simple and inexpensive report. It will give information regarding blood cells: Red blood cell, White blood cell & Platelet.



Normal count4 to 5.5 million/cu mm

Increasing RBC count more than 7 million/cu mm is known as polycythemia.
If it goes beyond 14 million/cu mm, than it may be due to cancer of red bone marrow. 

It decreases in anaemia.


Normal range – 14 to 16 g/dl

If HB decreases below normal range than it known anaemia.

Once Low HB detected than it may be due to iron deficiency anaemia, nutrition deficiency anaemia, sickel cell anaemia, thalassemia, etc. This will be find out by other blood reports.

Mean Corpuscular Volume (MCV)

MCV is the average volume of a single RBC.
Normal range – 78 to 90 fl

Level of MCV increases in vitamin B12 deficiency that causes megaloblastic & pernicious anaemia.

Level of MCV decreases in Iron deficiency anaemia.

Mean Corpuscular Hemoglobin (MCH)

MCH is the quantity or amount of hemoglobin present in one RBC.
Normal range – 27 to 32 pg

Mean Corpuscular Hemoglobin Concentration (MCHC)

MCHC is the concentration of hemoglobin in one RBC. 

Normal value – 32 to 36%


White blood cells (WBCs) or leucocytes are the colorless and nucleated formed elements of blood. It is known as soldiers which protects our body from so many infections.

WBC devide into five types

  • Neutrophils
  • Lymphocytes
  • Eosinophil
  • Basophil
  • Monotype

We need to understand total white blood cells with their types, to understand CBC report.


WBC normal range4000 to 11000/cu mm

The duty of WBC is to protect our body from infection. So, its obvious that while we have any bacterial or other infection, the numbers of WBCs will increases to protect our body.

So, White blood cells more than 11000 suggest infection in body. It also increases in allergy, common cold, tuberculosis & glandular fever.

Increasing white blood cell more than 100,000 suggest blood cancer.

In some situations WBC count decreases below 4000/ cu mm. It occurs in below conditions

This is very important part & its beauty of CBC report. Because once WBC count decreases, you need to find out the cause of it. This leads to proper diagnosis and treatment. 


Normal range – 50 to 70% of total WBCs

In some conditions neutrophil count increases 

  • Acute infection
  • Metabolic disorder
  • Injection of foreign proteins
  • Injection of vaccines
  • Poisoning like lead, mercury camphor, etc.
  • Poisoning by insect venom
  • After acute hemorrhage

In some conditions neutrophil count may decreases

  • Bone marrow disorders
  • Typhoid
  • Tuberculosis
  • Vitamin deficiency
  • Autoimmune disease


Normal range – 20 to 30% of total WBC

Lymphocyte count increases in below conditions

In some disease conditions lymphocyte count may decreases

  • AIDS
  • Cancer of lymphatic system
  • Radiation therapy
  • Steroid administration


Normal count – 2 to 4% of total WBC

This count increases in conditions like

  • Allergy or asthma
  • Blood parasite
  • Intestinal parasite

It decreases in conditions like

  • Bacterial infections
  • Stress
  • Taking steroid, epinephrine drug for long time
  • Cushing syndrome


Normal range – 150,000 to 450,000/cu mm

Platelet count decreases below 150,000/cu mm is alarming & it suggest to find out disease condition in body with help of other reports.

In general practice when patient comes with history of fever & CBC report suggest low platelet. Than doctor do other reports for malaria, dengue, typhoid as needed with history of patient’s complain. If not find anything than it may be due to viral fever.

Increasing platelet count more than 450,000/cu mm is rare but it may be due to below conditions

  • Allergic conditions
  • Asphyxia
  • Hemorrhage
  • Bone fracture, surgical operation, injury
  • Removal of spleen
  • Rheumatic fever

The normal range of any cells may be different from source to source. Slight variation in any count may be normal for particular individual. So, follow advise of your consulting doctor.

When there is abnormal counts comes in Complete blood count (CBC) report, your consulting doctor will prescribe medicines to make it normal. Eg. if hemoglobin comes low than doctor gives medicines to increase HB. Side by side it is also important to find of cause of low HB with help of other reports.

If low platelet comes in CBC report in fever conditions than your doctor will repeat test many times while treatment to monitor disease conditions.

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