Complete Blood Count (CBC)

The complete blood count (CBC) is one of the most frequently ordered blood tests. It is essential to know that blood consists of two major parts: plasma and cellular elements. The plasma is the part of the blood that is liquid, which allows the blood to flow smoothly. The other part of the blood consists of blood cells.

The blood cells are white blood cells (WBC)red blood cells (RBC), and platelets. Each of these types of cells carries out specific and vital functions.

The complete blood count test measures the quantity of all the different types of cells in the blood. It also provides some valuable information on other parameters related to each type of blood cell.

How does a complete blood count (CBC) test is made? Blood is collected by inserting a needle into a vein and allowing it to flow into a tube. Later the blood sample gets to the laboratory, and the red blood cells, white blood cells, and platelets get counted. The CBC is used to test for, diagnose, and monitor many different conditions.

The CBC test gets a lot of information from your blood sample:

  • White blood cells (WBCs) their number and their types. Your body has five kinds of white blood cells. All play a role in fighting infections. High numbers of WBCs, or a specific type of WBC, may mean you have an infection or inflammation somewhere in your body. Low numbers of WBCs may mean you are at risk for infections.
  • Numbers of the red blood cells (RBCs). RBCs carry oxygen throughout the body and remove excess carbon dioxide. Too few RBCs may be a sign of anemia or other diseases. In rare cases, too many may cause problems with blood flow.
  • The size of your red blood cells varies. This test is known as the red cell distribution width (RDW). For instance, you may have more significant differences in red blood cell size if you have anemia.
  • Hematocrit. The portion of red blood cells in a certain amount of whole blood. A low hematocrit may be a sign of too much bleeding. Or it might mean that you have iron deficiency or other disorders. A higher than average hematocrit occurs when one is dehydrated or by some other conditions.
  • Hemoglobin. Hemoglobin is a protein in red blood cells. It carries oxygen from your lungs to the rest of the body. Abnormalities can be a sign of problems ranging from anemia to lung disease.
  • Red blood cells average size. This test is known as the mean corpuscular volume (MCV). MCV goes up when your red blood cells are bigger than expected. It happens if you have anemia caused by low vitamin B12 or folate levels. If your red blood cells are smaller, this can mean other types of anemia, such as iron deficiency anemia.
  • A platelet count. Platelets are cell fragments that play a role in blood clotting. Too few platelets may mean you have a higher risk of bleeding. Too many may tell several possible conditions.
  • Mean corpuscular hemoglobin. This test measures how much hemoglobin your red blood cells have.

Haemoglobin (g/L)

Optimal range: 138 - 151 g/L

Hemoglobin (Hb) is the iron-containing oxygen transportation protein in red blood cells. It's rate of binding oxygen depends on the number oxygen molecules already bound.


A hematocrit test (Hct) is a simple blood test that measures the percentage of red blood cells in your blood. Red blood cells are important because they carry oxygen throughout your body. Test results showing low or high hematocrit levels may be signs of blood disorders or other medical conditions.



Optimal range: 13 - 17.7 g/dL

What is hemoglobin?

Hemoglobin is the main component of red blood cells. Hemoglobin (abbreviation: Hb) is a red substance made of iron and protein.

What's the function of hemoglobin?

- In the blood, it carries oxygen to the cells in the body from the lungs.

- Hemoglobin also carries carbon dioxide away from the cells to the lungs, later exhaled from the body. Carbon dioxide is a colorless and odorless gas present in small amounts in the air. It is a result of metabolism in the body. Metabolism is the chemical action in cells that release energy from nutrients or use energy to create other substances.

What are normal reference ranges for hemoglobin?

Normal hemoglobin levels differ depending on several factors, including age, sex at birth, hormonal supplementation, altitude of residence as well as presence of different hemoglobin types that impact hemoglobin turnover and affinity for oxygen binding.

Like other blood values, slightly high or low levels of hemoglobin may be normal for some people. Still, suppose you are falling too far out of the normal range. In that case, your doctor will most likely order more comprehensive testing to determine the cause. 


Mean Cell Volume

Optimal range: 75 - 95 fL/red cell

Mean cell volume indicates the average volume of red blood cells in the body. It is often measured as a part of the red blood cell indices in a comprehensive blood count test. The results of the red blood cell indices will tell a healthcare professional whether or not anemia is present and, if so, what type it is.


Mean Corpuscular Hemoglobin (MCH)

Optimal range: 26.6 - 33 pg

Mean corpuscular (or cell) hemoglobin (abbreviated as MCH) is an estimate of the amount of hemoglobin in an average red blood cell. Hemoglobin is a substance in the blood that carries oxygen to the cells in the body from the lungs.


MCHC stands for mean corpuscular hemoglobin concentration. MCHC is part of the red cell indices, together with MCH and MCV. Those parameters reflect the size and hemoglobin content of red cells. They have traditionally been used to aid in the differential diagnosis of anemia.


Mean Corpuscular Volume (MCV)

Optimal range: 79 - 97 fl

Mean corpuscular volume indicates the average volume of red blood cells in the body. It is often measured as a part of the red blood cell indices in a comprehensive blood count test. The results of the red blood cell indices will tell a healthcare professional whether or not anemia is present and, if so, what type it is.


Mean Platelet Volume (MPV)

Optimal range: 7.5 - 11.5 fl

Mean platelet volume (MPV) is a calculation that indicates the average size of platelets in the blood. This measurement is typically done during a comprehensive blood count. An abnormal MPV is not, in it of itself, an indication of disease or disorder. MPV scores are compared against other types of blood counts to give a healthcare professional more information about a potential medical issue.


Platelet count / Platelets

Optimal range: 150 - 450 µl

Other names: Platelets, Thrombocyte Count

What are platelets?

Platelets (aka thrombocytes) are small, colorless cell fragments in our blood that form clots and stop or prevent bleeding. 

Where are platelets made?

Platelets are made in our bone marrow, the sponge-like tissue inside our bones. Bone marrow contains stem cells that develop into red blood cells, white blood cells, and platelets.

What is the main function of platelets?

Platelets form clots when there’s damage to a blood vessel. For example, if you cut your finger, platelets mix with coagulation factors/clotting factors (proteins in the blood). Together, they form a “glue” that stops the bleeding.


Platelet Distribution Width (PDW)

Optimal range: 9.2 - 16.7 fl

This marker can give you additional information about your platelets and the cause of a high or low platelet count. Larger platelets are usually younger platelets that have been released earlier than normal from the bone marrow, while smaller platelets may be older and have been in circulation for a few days.


Platelet-large cell ratio (P-LCR)

Optimal range: 16 - 41.3 %

Platelet-large cell ratio (P-LCR) is defined as the percentage of platelets that exceed the normal value of platelet volume of 12 fL in the total platelet count.

Platelet size has been shown to reflect platelet activity; therefore MPV (=Mean Platelet Volume) and P-LCR are a simple and easy method of indirect assessment of platelet stimulation.


RDW-CV (Red Cell Distribution Width) in %

Optimal range: 11.7 - 15.4 %

The RDW value tells you whether enough of your red blood cells are of normal size and shape.

Why is this important?

The red blood cells are usually flat and lenticular (disc-shaped) with a diameter of around 7.5 µm (micrometer).

Blood cells must squeeze through the body’s smallest blood vessels, the above described capillaries, to do their job, but capillaries often become narrower than the cells in their normal disc shape. Capillaries can be as small as 4 µm in diameter. So the cells must deform and “curl up” to fit through those capillaries. Remember a normal red blood cell is around 7.5 µm in diameter.

Only when this process of “squeezing” through capillaries can happen, the supply of oxygen is guaranteed throughout the whole body.

Some red blood cells are however not optimally formed. To a certain extent this is normal as there are 2 million red blood cells formed per second. Usually there are around 85% to 89% of red blood cells developed properly.


Red cell distribution width (abbreviated as RDW) is a measurement of the amount that red blood cells vary in size. Red blood cells help carry oxygen in the blood.


Red Blood Cells (Erythrocytes / RBC)

Optimal range: 4.14 - 5.8 cells/mcL

Other names: erythrocyte count, red count

Red blood cells carry oxygen from the lungs to the rest of the body. They also carry carbon dioxide back to the lungs so it can be exhaled. Red blood cells (RBC) are made in the bone marrow and contain hemoglobin, a protein that carries oxygen to the tissues in the body. These cells are also known as erythrocytes.

Anemia is a condition that results from a decrease in the number of RBCs. Elevated RBC counts are seen in other conditions where there is low oxygen levels, certain drugs, kidney disease, or bone marrow overproduction. If your RBC count results are abnormal, additional tests are usually done to diagnose the cause of the high or low level of red blood cells.

A CBC measures two other components of your red blood cells:

- hemoglobin: oxygen-carrying protein

- hematocrit: percentage of red blood cells in your blood

Abnormal levels of red blood cells, hemoglobin, or hematocrit may be a sign of anemia, heart disease, or too little iron in your body.


White blood cells (Leukocytes / WBC)

Optimal range: 3.4 - 10.8 x10E3/µL

White blood cells, often called leukocytes, are three types of cells found in the blood, along with red blood cells and platelets. Specifically, the white blood cell family contains five members: monocytes, lymphocytes, basophils, neutrophils, and eosinophils. Together, these five cells act as our body’s primary immune system, responding to irritants and invaders. All blood cells are made in the bone marrow and then pass into the bloodstream. Leukocyte levels in the body are assessed through a blood differential test (also called a white blood cell differential) as a part of a complete blood count. This test can detect abnormal or immature cells and diagnose an infection, leukemia, or an autoimmune disorder. A healthcare professional may order a blood differential when someone has general signs and symptoms of infection and/or inflammation, such as:

- Fever, chills

- Body aches, pains

- Headache