CBC (HH-RBC-WBC-PLT)

Also Known As:  Blood Count, CBC, CBC W/Diff, PLT, RDW, CBC/DIFF, Coulter CBC, Platelet Count, Hematocrit, Hemoglobin

What Is A CBC (H/H, RBC, Indices, WBC, PLT) Test?

A complete blood count or CBC is one of doctors' most commonly and frequently suggested blood tests. This blood test is used to evaluate your overall health condition and a wide range of disorders, including blood infection, anemia, and leukemia. Your blood comprises two main parts, i.e., cellular elements and plasma.

Plasma is the liquid part of the blood that allows it to flow smoothly in the body. The cellular elements, on the other hand, include blood cells. These blood cells are red blood cells (RBCs), white blood cells (WBCs), and platelets. Each one of them is different and carries out its specific vital function. The CBC test analyzes, diagnoses, and monitors these blood cells. Your doctor can get a CBC test done to obtain information regarding your blood sample.

What Is The Test Used For?

Remember that a complete blood count is the most common blood test a doctor can perform for a wide range of reasons such as:

• To Diagnose A Particular Health Condition

A doctor or health care provider recommends a complete blood count test if you are experiencing fever, extreme weakness, fatigue, bruising, bleeding, or inflammation. This test can help diagnose the causes of any of these symptoms and signs. If your doctor thinks you have an infection, the complete blood count can confirm the diagnosis and help plan a suitable treatment.

• To Review Your General Health

For many people, the complete blood count is a part of their routine medical examination. A doctor may require the test results to monitor your general health and to screen your body for a wide range of disorders like leukemia on anemia.

• To Monitor Certain Health Conditions

After careful diagnosis with a CBC test, your health care provider can also use the readings to monitor the blood disorder affecting your blood cell count.

• To Scrutinize The Medical Treatment

A CBC or complete blood count is also used to monitor your health, especially if you take certain medications that affect blood cell size and count.

Why And When Do You Need CBC (H/H, RBC, Indices, WBC, PLT) Test?

You might need a CBC (H/H, RBC, Indices, WBC, PLT) Test if you are showing signs and symptoms like:

• Extreme fatigue
• Weakness or dizziness
• Bleeding
• Bruising
• Problems with your blood pressure or heart rate
• Inflammation, irritation, or swelling of the body
• Severe joint pain

Know that a complete blood count is essential for your physical examination. Your health care provider can also recommend this test to check out the side effects of some prescribed medicines. In most cases, the CBC blood test is limited to measuring and studying white blood cells, red blood cells, and platelets. 

Red blood cells are responsible for carrying oxygen throughout your body; white blood cells are an integral part of the immune system, so they help fight infection. Platelets help your body form blood clots. With a complete blood count, your doctor will evaluate and study several aspects of your blood, including:

• Complete blood count without differential ( to count the total number of white blood cells in the blood)
• Complete blood count with differential ( this differential looks at the number of different types of white blood cells that you may have)
• Hematocrit ( it is the concentration of red blood cells in the bloodstream)
• Hemoglobin ( it is the protein present in red blood cells that carry oxygen to all parts of your body)

Your provider will know:

• The number of new blood cells your body is producing
• The size and shape of your blood cells
• The number of red blood cells or erythrocytes, white blood cells or leukocytes, and platelets

Once the test results arrive, the CBC can help your doctor diagnose a variety of diseases, disorders, medical conditions, and infections, including:

• Bone marrow disorders like myelodysplastic syndrome
• Anemia ( a condition in which there are not enough red blood cells to carry oxygen throughout your body organs)
• Vitamin and mineral deficiencies
• Diseases like thalassemia, agranulocytosis, and Sickle Cell anemia
• Side effects of chemotherapy and other special prescription medicines
• Different types of cancer like lymphoma or leukemia
• Infections and other medical problems causing abnormally low or high white blood cell count

What Kind Of Samples Is Required For The Test?

A CBC (H/H, RBC, INDICES, WBC, PLT) test needs a needle blood draw which is most commonly performed by a licensed, professional lab assistant or health care provider in a hospital setting or a doctor's office. Your test part is quite simple and will only take a few minutes.

Do You Need To Prepare For The Test?

Since it is a simple blood test, you don't need to do anything special to prepare for a CBC. 

The one performing the test will clean your arm and insert a needle. The needle might pinch or sting you a little, but it should not hurt a lot. 

After taking the blood, the nurse will remove the needle and put a bandage on your arm so your body can quickly rebuild its normal blood supply. Before the test, you can eat and drink normally, but if your doctor wants to perform additional tests, you may need to fast for a certain amount of time before giving out the blood sample.

Are There Any Risks To This Test?

A complete blood count or CBC is one of the safest, most common tests required for physical examination. In rare cases, people might feel a bit dizzy, lightheaded, or even faint, but the symptoms do not last long.

What Do The Test Results Mean?

Measurements Of Red Blood Cells

Since red blood cells carry oxygen throughout your body, the RBC count in CBC indicates the total number of red blood cells in the bloodstream. Hemoglobin and hematocrit are also other measures linked to your red blood cells. Low levels of red blood cells indicate anemia, but there can be other potential causes of abnormally low levels of RBCs, hemoglobin, and hematocrit, such as:

• Chronic illnesses with inflammation or disrupted organ function
• Excessive chronic or acute bleeding
• Different types of cancer as well as cancer treatments
• Destruction of red blood cells in a condition called hemolytic anemia
• Nutritional deficiencies due to low vitamin b12, iron, or folate
• Diseases affecting bone marrow produce new red blood cells

High levels of red blood cells, hemoglobin, and hematocrit can also be due to several reasons, for example:

• Excessive smoking
• Dehydration
• Different types of kidney diseases
• Lung or heart diseases reduce oxygen levels
• Polycythemia vera a rare disorder in which there is an overproduction of red blood cells in the body

In many cases, your CBC will also include certain measurements called RBC indices involving mean corpuscular hemoglobin (MCH), mean corpuscular volume (MCV), and mean corpuscular hemoglobin concentration (MCHC). These indices help distinguish among the causes of anemia.

Measurement And Count Of White Blood Cell

When it comes to your immune system, know that white blood cells are the main players. White blood cell count consists of five different kinds of blood cells with their distinctive role in immune function. Having too many white blood cells is termed leukocytosis, which can be due to multiple potential causes:

• Certain prescription medications
• Infections and allergies
• Tissue death from burns, injury, and other physical trauma
• Stress and anxiety
• Leukemia and other forms of cancer

A low level of white blood cells is known as leukopenia. There are many causes of leukopenia, such as:

• Some prescription medications involving the ones for cancer chemotherapy
• Liver damage due to excessive alcohol use/abuse
• Medical conditions that disrupt the bone marrow function
• Severe infections in the body
• Autoimmune disorders
• A damaged or enlarged spleen

People who get their CBC done with WBC differential can have the results of each kind of white blood cells. These are called neutrophils, lymphocytes, monocytes, eosinophils, and basophils. The specific levels of these types can give detailed information to your doctor and help him interpret the findings.

Platelet Count

Too many platelets lead to thrombocytosis, which is linked with a higher risk of cardiovascular complications due to blood clots. An abnormally high platelet count can be due to several conditions:

• Bone marrow dysfunction
• Iron deficiency
• Some forms of cancer
• Tissue trauma or any recent infection

Low platelet count is termed thrombocytopenia, a condition with risks related to bruising or bleeding. Some of the possible causes of a low platelet count are:

• Damage to the bone marrow
• Pregnancy or lactation
• Blood disorders leading to platelet destruction
• Special medicines loading dose of chemotherapy
• Enlarged spleen

The test also helps measure the mean platelet volume, i.e., MPV. It is the size of your platelets and helps the doctor understand how fast or slow your body is producing new platelet cells.

Related Tests:  Red Blood Cell Count, Hematocrit Test, Blood Smear, Hemoglobin Test

Our clinical experts continually monitor the health and medical content posted on CURA4U, and we update our blogs and articles when new information becomes available. Last reviewed by Dr.Saad Zia on January 09, 2024. 

References

qt2x4029rz_noSplash_7cdb4ca9487e306b0f5eb714873c2395.pdf (escholarship.org)

https://escholarship.org/content/qt2x4029rz/qt2x4029rz_noSplash_7cdb4ca9487e306b0f5eb714873c2395.pdf

Optimization of laboratory services and education at the UCSD student-run free clinic project during electronic health record and laboratory information systems integration (escholarship.org)

https://escholarship.org/uc/item/2x4029rz