An FBC (Full Blood Count) or CBC(Complete Blood Count) Test
I’m sure every single person reading this article who has had a blood test done at some point in his or her lives has come across this test. It is probably the most routinely ordered blood test in the world. In most clinics even if you just catch a cold a doctor would order this test to show you that he has done some work even if it is not necessary.
So what is an FBC or CBC Test?
Well it is exactly what is says, A complete blood picture.
Your blood has three main types of cells floating around in it with different functions for each of them
RBCs or Red Blood Cells , these guys carry around oxygen and nutrition.
WBCs or White Blood Cells, there are about 5 different types of them and they form the defense department of your body. Just like the navy, army, air force etc in a defense department, each has their own areas to take care of.
Platelets – These guys get together and plug a tear or a wound when it happens so that you don’t bleed to death.
So let’s look at the tests and figure out what an increased level or decreased level of each would mean
I have taken a real life report, which would be what most people would see these days when they get one.
Looks confusing doesn’t it?
To make things easier I have shaded out the components that you don’t need to look at from a common man perspective. This will make it look less mind-boggling. At a very basic level you just need to look at the three parts mentioned above, the RBC’s , WBC’s and Platelets. Normal reference values will be shown next to the lab result values in all reports so that you can tell if the levels are increased or decreased.
Here it is once again showing the important areas.
Lets Take the RBC’s and Hemoglobin levels first.
RBC’s are the red blood cells which carry oxygen and nutrition. They contain a protein called Hemoglobin– Heme means iron and globin is a protein so heamglobin can be considered as iron containing protein. The iron inside hemoglobin helps carry oxygen.
So let’s say you have a heavy bleeding episode, maybe in an accident or maybe you have some bleeding within your body through an undetected stomach ulcer. Since you are losing blood the RBC levels would drop. This would drop your hemoglobin levels as well.
This is called anemia.
Anemia can also be because the production of RBC s are slow in your body possibly through nutritional deficiencies like Vitamin B12 or low Iron in the food, and not just through blood loss
So next time you see a reduced RBC level chances are you have low production of RBCs or you have had some degree of blood loss. If you have low hemoglobin levels along with that, your doctor would prescribe you iron with Vitamin B12 tablets.
Increased levels of RBCs occur in a condition called polycythemia. This means you need to a visit to a hematologist who is a specialist in blood related issues.
Moving on to WBCs.
As mentioned earlier these guys form the major part of your defense system in the body. You would see a WBC Total count and then 5 other counts, which make up the WBC Total Count.
WBC Total count consists of
Neutrophils– If this value is increased that means you have an active infection going on. They are usually markedly raised when there is a bacterial infection. Examples are Tonsillitis, Sinusitis, Meningitis, Pneumonia , etc….
Decreased levels of Neutrophils will affect your body’s ability to fight infections and is called Neutropenia.
Lymphocytes – If you see an increase in this count it can mean that you could have an ongoing viral infection like cytomegalovirus (CMV) infection, human immunodeficiency virus (HIV), mononucleosis or a whole lot of other viral infections. Lymphocytes can also be raised in acute lymphocytic leukemia, chronic lymphocytic leukemia and multiple myeloma, which are different types of blood cancers.
Once again you need expert medical advice from a hematologist to ensure the raised lymphocyte levels are nothing serious as sometimes they can be raised in normal individuals as well.
Decreased levels of Lymphocytes will also affect your body’s ability to fight infections and is called Lymphocytopenia.
Eosinophils– If you see an increase in this count it could be one of the following in most common situations.
An allergic reaction or a parasitic infection
Much more uncommon conditions are an autoimmune disease where your body attacks its own cells or blood cancer.
These guys are more related to allergic reactions than the remaining 4 WBCs
Monocytes– It is a much rarer finding to have a raised monocyte count compared to Neutophils, Eosinophils and Lymphocytes.
Monocytes play an active role in the blood by literally eating up specific infective organisms. In medicine this would be called phagocytosis.
If this happens to be raised it could indicate a very long standing persistent infection , some form of blood cancer or an autoimmune disease.
Basophils – These cells are also related to allergic reactions particularly in case of asthma. Although they contribute to the overall purpose of fighting infections they are actively involved in allergic reactions such as atopic dermatitis(Allergic skin rashes), inflammatory bowel disease , asthma, etc….
Finally the Platelets
These guys serve the primary function of plugging an open wound when it happens. When a cut occurs, signals are sent through the bloodstream notifying cells of the trauma. Platelets in the blood release chemicals that notify other platelets nearby to become sticky. Once activated, platelets change shape by growing small projections. This helps them to stick together.
A protein in the blood called fibrinogen has become active as well. It is now called fibrin, and as its name suggests, it produces fibers. These strands cover the wound and create a web of sorts, similar situation to hairs clogging a drain.
The activated platelets continue to arrive on the scene through the bloodstream. They stick together and become caught in the web of fibrin. Red blood cells become trapped as well. Again, imagine that drain clogged with hair. If you added bits of paper to that drain on top of the hair, it would most certainly create a totally blocked drain. This is how the bleeding is stopped in real time.
If you have a decrease in platelets, your bleeding time would increase and of course if you are very low then you could bleed to death.
On the contrary if you have very high number of platelets you could start have too many clots forming in your blood stream and this could block the flow of blood in various organs causing organ failure, stroke or a heart attack.
So there you have it.
What to look for in a Complete Blood Count or Full Blood Count and what they mean.
- Low or High RBC count and Haemoglobin count
- Low or high WBC count
- Low or high Platelet count
That’s a summary of what a common patient should look for in a complete or full blood count test ordered by the doctor.
Please do not self diagnose yourself with any of this information; it is only a brief guide to help you understand what is going on.
