When visiting your doctor for an illness or condition, you might be asked to undergo a routine blood test called a “CBC” or a “Complete Blood Count.” This is a vital assessment used by your physician to diagnose your condition and suggest a treatment.

The procedure requires blood usually drawn from the inside elbow of the patient. The sample is then processed by an automated hematology analyzer, which counts blood particles, as well as ascertain their size and shape.

The CBC test result is like a magnifying glass that your doctor uses to gain richer insights into your state of health.

A CBC can also reveal the possible impact of present medication on the patient’s health—if at all. But whatever the case, a CBC looks into three elements in the blood: red blood cells, white blood cells, and platelets.

Here we take a closer look at some of the numbers that you might find in a CBC result.

Red Blood Cells

Red blood cells comprise around 45% of the blood. There are about 5 million red blood cells (or erythrocytes) in a single drop of blood. These are cells produced in the bone marrow and have a life span of 120 days.

There are 2.5 million blood cells produced every second, and they have a very important function. They transport oxygen to the different parts of the body. Through blood circulation, oxygen reaches the tissues and other vital organs. Without it, cells cannot perform even their most basic functions.

Standards may differ depending on factors like gender or age, but according to the Philippine Heart Center, the normal range of values for RBC is  4.5 – 5.2 x 10 12/L for men and 4.0 – 4.5 x 1012/L for women.

(Before continuing, it is important to note that a CBC is just one of the diagnostic tools your physician uses to diagnose a condition. Having “high” or “low” results can have a myriad of causes and do not necessarily pinpoint a disease. Going above or below the range of values does not automatically suggest something is wrong. It can be harmless and temporary. Oftentimes, your doctor will suggest further tests to look into a condition.)

Low RBC Count: A patient with low RBC may feel weak, tired, and light-headed. A low reading could indicate some vitamin deficiency, like folate, vitamin B6/B12—or kidney disease or anemia.

As previously mentioned, the low count can be symptomatic of many things and your physician is in the best position to diagnose the cause. Nevertheless, a low RBC means the body needs to work harder to get oxygen into the different organs and tissues.

High RBC Count: Like in the case of low RBC count, it’s difficult to pinpoint a culprit. A high RBC would be indicative of conditions like heart disease, sleep apnea, Polycythemia vera, etc.

The body could be compensating for low oxygen levels so it is producing more RBC. This can be brought about by a range of conditions—from lung disease to living in high altitudes where the air is thin. 

Smoking and performance-enhancing drugs are also thought to increase RBC counts.

Counting RBCs is not enough to ascertain the character of an individual’s red blood cells. One can look at them in many different ways. A CBC result might look like this:

1) Hemoglobin

Normal Ranges:

Male = 140-170 g/L

Female = 120-150 g/L

Hemoglobin is the component in the blood that carries oxygen. By measuring hemoglobin levels, you have an insight into how much oxygen is carried by your red blood cells. Going below the normal range typically means your tissues and organs are not getting sufficient amounts of oxygen. High hemoglobin, on the other hand, can be a sign of lung or heart disease.    

2) Hematocrit

Normal Range:

Male = 42% -51%

Female = 37% – 47%

Blood is composed of red blood cells, white blood cells, platelets, and plasma. Hematocrit measures the percentage of red blood cells in your blood. It’s an important indicator of an individual’s general condition. So when donating blood, for example, there’s a minimum hematocrit level required.

A result below normal can signal anemia, while a result above the normal range could indicate conditions like polycythemia or erythrocytosis.

3) MCV

Normal Range: 80-96 fL

MCV stands for “Mean Corpuscular Volume.” This refers to the average size of an individual’s red blood cells. A low result means the patient’s RBCs are smaller than the accepted standard, while a high result means the cells are bigger than normal.

Looking at the average size of these cells allows doctors a deeper look into an individual’s condition. It’s especially useful when zeroing on a specific blood abnormality.   

4) MCH and MCHC

MCH Normal Range: 27.5-33.2 pg

MCHC Normal Range: 334 – 335 g/L

MCH stands for “Mean Corpuscular Hemoglobin,” and MCHC stands for “Mean Corpuscular Hemoglobin Concentration.” These measures are very similar and they seek to establish the average amount of oxygen contained in each of these RBCs. (You might have plenty of RBCs but are carrying low levels of oxygen.)

We have several measurements for hemoglobin levels because oxygen is vital to the normal functioning of cells, tissues, and organs. These different indices look at hemoglobin from different reference points in order to get a clearer picture of how effectively oxygen is distributed to the rest of the body.

5) RDW

Normal Range: 11.6% – 14.6%

RDW means “Red Cell Distribution Width.” It is a measure of the variability of the sizes of your red blood cells. RBCs are generally of the same size. This test looks into how uniformly-sized your RBCs are. A low RDW means your red blood cells are all about the same size. A high result means you have a mix of very small RBCs and very large RBCs.

A high RDW may signal some nutrient deficiency.   

White Blood Cells

White blood cells or leukocytes are part of the body’s immune system. They are a class of cells that, like soldiers, defend the body from pathogens such as germs and viruses.

White blood cells comprise just 1% of the blood but form an important part of the CBC test. White blood cells are produced in the bone marrow and are found in the bloodstream as well as the lymph tissues.

There are many different types of WBCs. You have the lymphocytes (T-cells and B-cells), the granulocytes (neutrophils, eosinophils, and basophils), and the monocytes. Because of their often short lifespan (1-3 days), the bone marrow needs to produce them continuously.  

The range of values for a normal WBC count is between 5.0 - 10.0 x 10 9/L both for men and women.

Low WBC Count: A low WBC could mean:

a) that the bone marrow is not functioning properly

b) white blood cells are being used up faster than they are being produced

c) medication is affecting the production and retention of WBCs.

The underlying causes can range from malnutrition to HIV. A low WBC can mean nothing. But in extreme cases, it can indicate conditions like leukemia, lupus, rheumatoid arthritis, tuberculosis, or aplastic anemia.

When there are few white blood cells in the blood, it means that the patient does not have enough soldiers to fight any infection, leaving the patient susceptible to a host of illnesses.

High WBC Count: An opposite condition, that of having too high WBC in the blood, could mean that your body is fighting a viral or bacterial infection. It means your body is working overtime to destroy a perceived threat or invader. Autoimmune diseases can increase WBC production as well.

Inflammation, physical and emotional stress, burns can also cause a spike in the WBC. Smoking can even cause that as well.

In truth, there are many types of white blood cells. It’s often better to get a differential count and look at the relative percentages of each type of WBC.

1) Neutrophils

These are the most common type of WBCs, comprising around 40%-60% of the white blood cells. They are the primary defense against infections and major injuries and are therefore elevated when the immune system responds to an attack, like a bacterial infection.

Neutrophils can pass through the walls of the blood vessel, leave the bloodstream, and go directly to the tissues. They also help wounds heal faster.

A low neutrophil count could mean that the body is burning through them too quickly or is not producing enough of them.  

2) Lymphocytes

Lymphocytes are around 20%-40% of WBCs. They have many functions in the immune system, one of which is the formation of antibodies for specific diseases. For example, a memory B-cell “remembers” viruses of the past and can quickly mount a counter-attack.

Another kind of lymphocyte, the killer T-cell, scans for infected cells in the body. When it finds one, it quickly resolves the issue by killing the cell.

An elevated lymphocyte count would signal an infection. A low lymphocyte count can be harmless. But, considering the possibility that the low count is due to lymphocytes being used up faster than they are being produced, it can point to some underlying condition—like an autoimmune disease, immunodeficiency, even renal failure.  

3) Monocytes

Monocytes are another vital component of the immune system. They comprise 2%-8% of WBCs. One type of monocyte is the macrophage—a huge cell that’s 3-4 times larger than a red blood cell. Monocytes perform a variety of functions, one of which is to kill infected cells by “eating” or ingesting them.

Monocytes help destroy cancer cells.

Some conditions that cause an elevated monocyte count are parasitic infections, mumps, measles, leukemia, and tuberculosis. A low level might be due to immunosuppression of some sort.

4) Eosinophils

Eosinophils are 1%-4% of WBCs. They are mainly involved in parasitic infections, asthma, and allergy responses—where a high count suggests that the individual is experiencing these events.

Low levels of eosinophils are generally not a cause of concern.

5) Basophils

Basophils are the least common type of white blood cell and just comprise 0.5%-1% of WBCs. Like eosinophils, they also respond to allergies.

Basophils release histamine that in part causes inflammation during an allergic reaction. They also contain heparin, which has anticoagulant properties, promoting blood flow during an immune response.

High levels of basophils can result in inflammation, while low levels can point to issues like hyperthyroidism.

Platelets

Platelets are aptly named because, viewed under the microscope, these cells look like small plates.

Their main function is to prevent bleeding by causing blood to clot. Platelets rush to the area where there is blood vessel damage. They cause blood clots by sticking to one another and forming a barrier or plug.

Like RBCs and WBCs, platelets are also produced in the bone marrow. Once released in the bloodstream, they can last around 8-10 days.

The reference range for platelets is 200- 400 x 109/L.

Low Platelet Count: A low platelet count means the body has reduced capacity to close up wounds and is in danger of bleeding. It can be a potentially dangerous condition because the bleeding can happen internally. In some cases, a simple bruise can become a serious issue.

Low platelet counts have been observed in conditions like dengue, leukemia, lymphoma, and some types of anemia.  

High Platelet Count: Excessively high numbers of blood platelets can make the blood overly sensitive to clotting (thrombosis). That is, there may be blood clots in places and instances when they are not needed. Unnecessary blood clots impede the smooth flow of blood and could potentially block the vital organs from getting ample oxygen and blood.   

These are just some of the things your doctor can know by reading your results. A Complete Blood Count could give you a behind-the-scenes look at the state of your health.

Interested in a CBC?

BloodWorks Lab is your one-stop-shop for all your blood test needs. Besides our blood chemistry, hematology, and screening tests, we are proud to be the first laboratory in the Philippines to offer neurological assessments like the Anti-NMDA Receptor Antibody Test and the Anti Acetylcholine Receptor (lgG) Antibody Test.

Our branches are in Alabang, Katipunan, and Cebu.