Our GP is ready to help you if you want to be sure that you are healthy and in good shape, you have medical questions or problems and want to discuss with an experienced doctor, you have some unknown symptoms and want to know what they could be related to, you want to know another medical opinion about the best way of treatment of your disease.
A complete blood count (CBC) provides important information about
the kinds and numbers of cells in the blood:
red blood
cells,
white
blood cells, and
platelets. A CBC can help a health professional
evaluate symptoms (such as weakness, fatigue, or bruising) and diagnose
conditions (such as
anemia, infection, and many other disorders).
A CBC test usually includes:
White blood cell (WBC) count. White blood cells
protect the body against infection. If an infection develops, white blood cells
attack and destroy the bacteria, virus, or other organism causing it. White
blood cells are bigger than red blood cells and normally fewer in number. When
a person has a bacterial infection, the number of white cells can increase
dramatically. The white blood cell count shows the number of white blood cells
in a sample of blood. The number of white blood cells is sometimes used to
identify an infection or to monitor the body's response to cancer
treatment.
White blood cell types (WBC differential). There
are five major kinds of white blood cells: neutrophils, lymphocytes, monocytes,
eosinophils, and basophils. Immature neutrophils, called band neutrophils, are
also included and counted as part of this test. Each type of cell plays a
different role in protecting the body. The numbers of each one of these types
of white blood cells give important information about the
immune system. An increase or decrease in the numbers
of the different types of white blood cells can help identify infection, an
allergic or toxic reaction to certain medications or chemicals, and many
conditions (such as
leukemia).
Red blood cell (RBC) count. Red blood cells carry
oxygen from the lungs to the rest of the body. They also help carry carbon
dioxide back to the lungs so it can be exhaled. The red blood cell count shows
the number of red blood cells in a sample of blood. If the RBC count is low,
the body may not be getting the oxygen it needs. If the count is too high (a
condition called polycythemia), there is a risk that the red blood cells will
clump together and block tiny blood vessels (capillaries).
Hematocrit (HCT, packed cell volume, PCV). This
test measures the amount of space (volume) red blood cells occupy in the blood.
The value is given as a percentage of red blood cells in a volume of blood. For
example, a hematocrit of 38 means that 38% of the blood's volume is composed of
red cells.
Hemoglobin (Hgb). Hemoglobin is the major substance
in a red blood cells. It carries oxygen and gives the blood cell it's red
color. The hemoglobin test measures the amount of hemoglobin in blood and is a
good indication of the blood's ability to carry oxygen throughout the
body.
Red blood cell indices. There are three red blood
cell indices: mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH),
and mean corpuscular hemoglobin concentration (MCHC). They are measured by a
machine and their values are determined from other measurements noted during a
CBC. The MCV shows the size of the red blood cells. The MCH value is the amount
of hemoglobin in an average red blood cell. The MCHC measures the concentration
of hemoglobin in an average red blood cell. These numbers help in the diagnosis
of different types of anemia.
Red cell distribution width (RDW). The RDW reports
whether all the red cells are about the same width, size, and shape. This helps
further classify the types of anemia.
Platelet (thrombocyte) count. Platelets
(thrombocytes) are the smallest type of blood cell. They play a major role in
blood clotting. When bleeding occurs, the platelets swell, clump together, and
form a sticky plug that helps stop the bleeding. If there are too few
platelets, uncontrolled bleeding may be a problem. If there are too many
platelets, there is a risk of a blood clot forming in a blood vessel. Also,
platelets may be involved in hardening of the arteries, or
atherosclerosis.
Blood smear. In this test, a drop of blood is
spread (smeared) on a slide and stained with a special dye. The slide is then
examined under a microscope. The numbers, size, and shape of red blood cells,
white blood cells, and platelets are recorded. Blood cells with unusual shapes
or sizes can help diagnose many blood diseases, such as leukemia,
malaria, or
sickle cell anemia.
A complete blood count is done on a sample of blood taken from a
vein.
Complete Blood Count (CBC) Results
Normal
Normal values can vary from lab to lab.
Normal values for the complete blood count (CBC) tests vary,
depending on age, sex, elevation above sea level, and type of sample. The
health professional may use all the CBC values to evaluate a condition. For
instance, the red blood cell (RBC) count, hemoglobin (Hgb), and hematocrit
(HCT) are the most important values needed to help decide if a person has
anemia, but the red blood cell indices and the blood smear also help guide the
diagnosis and suggest a possible cause for the anemia.
To assess white blood cell (WBC) count, your doctor will look at
both the number (WBC count) and the WBC differential. To determine whether
there are too many or too few of a certain type of cell, the doctor multiplies
the total count by the percentage of that particular cell. There are normal
values for the total number of each type of white cell.
4,000–10,000 WBCs per
microliter (µL)
In black people, the range is 2,800–10,000 WBCs per
µL.
White blood cell types (WBC
differential)
Neutrophils:
47%–77%
Band neutrophils:
0%–3%
Lymphocytes:
16%–43%
Monocytes:
0.5%–10%
Eosinophils:
0.3%–7%
Basophils:
0.3%–2%
Red blood cell (RBC) count
Men:
4.6–6.2 million RBCs per
microliter (µL)
Women:
4.2–5.4 million RBCs per µL
Children:
4.6–4.8 million RBCs per µL
Hematocrit (HCT)
Men:
40%–54%
Women:
37%–47%
Children:
31%–41%
Newborns:
44%–64%
Hemoglobin (Hgb)
Men:
14–18
grams per deciliter (g/dL)
Women:
12–16 g/dL
In general, a normal hemoglobin level is about one-third the
value of the hematocrit.
Red blood cell indices
Mean corpuscular volume (MCV):
80–100
femtoliters (fL)
Mean corpuscular hemoglobin (MCH):
28–32
picograms (pg)
Mean corpuscular hemoglobin concentration
(MCHC):
32–36
grams per deciliter (g/dL)
Red cell distribution width
(RDW)
Adults:
11.7%–14.2%
Platelet (thrombocyte)
count
140,000–450,000 platelets per
microliter (µL)
Blood smear
Normal:
Blood cells are normal in shape, size, and
number.
Greater than normal values may mean
A high white blood cell count can indicate
infection, inflammation, damage to body tissues (such as a
heart attack), severe physical or emotional stress
(such as a fever, injury, or surgery), kidney failure, or diseases such as
cancer. Very high levels of white blood cells can sometimes indicate
leukemia.
The number of neutrophils can be
increased by infection, heart attack, burns, severe stress, and the use of
corticosteroid medications. Neutrophils are decreased
by exposure to radiation, some kinds of infection (such as
HIV infection), lack of vitamin
B12 or folic acid, or an
autoimmune disease such as
systemic lupus erythematosus (SLE).
Band
neutrophils increase in response to severe infection, especially infection
caused by bacteria.
Lymphocytes are increased by some viral
infections, diseases that affect the immune system, and some types of
leukemia. Lymphocytes can be decreased by the use of
corticosteroid medications, conditions that affect the
immune system (such as
AIDS), malnutrition, and severe, long-term
illnesses.
Monocytes can be increased by infection with a virus or
fungus (like yeast), some types of cancer and leukemia, and
tuberculosis (TB).
Eosinophils can be
increased by allergies, some infections (especially those caused by
parasites), skin diseases, reactions to some
medications, some types of leukemia and cancer, diseases that affect the immune
system (such as systemic lupus erythematosus), and underactive
adrenal glands. Eosinophils can be decreased by severe
stress or
Cushing's syndrome.
Basophils can be
increased by some types of leukemia and cancer or a poorly functioning
thyroid gland. Basophils are decreased by pregnancy,
severe stress, and an overactive thyroid gland.
A high red blood
cell count means the blood contains too many red blood cells. High values can
be caused by a lack of oxygen (which can occur from living at high altitude),
smoking, exposure to carbon monoxide, long-term lung disease, kidney disease,
certain forms of heart disease or a rare disorder of the bone marrow (polycythemia vera).
A high RBC count can
also be caused by too little water in the body (dehydration), a
result of drinking too little; other causes include frequent diarrhea or
vomiting, excessive sweating, severe burns, and the use of
diuretics.
A high hematocrit value means
the blood contains too many red blood cells (a condition called polycythemia).
High values can be caused by a lack of oxygen (which can occur from living at
high altitude), smoking, exposure to carbon monoxide, long-term lung disease,
certain forms of heart disease, kidney disease, certain types of cancer, or
polycythemia vera, a rare disorder of the bone
marrow.
A high hematocrit value can also be caused by too little
water in the body (dehydration), a result of drinking too little; other causes
include frequent diarrhea or vomiting, excessive sweating, severe burns, and
the use of diuretics.
A high hemoglobin value means the blood
contains too many red blood cells. High values can be caused by a lack of
oxygen (which can occur from living at high altitude), smoking, exposure to
carbon monoxide, long-term lung disease, certain forms of heart disease, kidney
disease, or
polycythemia vera, a rare disorder of the bone
marrow.
A high hemoglobin value can also be caused by too little
water in the body (dehydration), a result of drinking too
little; other causes include frequent diarrhea or vomiting, excessive sweating,
severe burns, and the use of
diuretics.
A high mean corpuscular volume
(MCV) value may indicate alcoholism, liver disease, a lack of folic acid or
vitamin B12 that is causing
anemia (such as
pernicious anemia), or certain bone marrow
disorders.
A high number of platelets can be caused by severe
bleeding, infection, strenuous exercise, pregnancy, removal of the
spleen, iron deficiency,
polycythemia vera,
rheumatoid arthritis, some types of cancer and
leukemia, or a condition of unknown cause in which
platelets are overproduced (called essential thrombocytosis).
Lower than normal values may mean
A low white blood cell count can mean that
the body is not producing enough white blood cells. For example, this may occur
late in pernicious anemia or after cancer
chemotherapyor radiation therapy. An allergic
reaction to a medication may cause a low white blood count.
A low
white blood cell count can also result from chemotherapy, bone marrow failure
(aplastic anemia), viral infections,
malaria, alcoholism,
AIDS, and other conditions.
Low values for
the red blood cell count, hematocrit, or hemoglobin tests mean the blood does
not contain enough healthy red blood cells. This leads to an inability to
supply the body with enough oxygen (anemia).
Anemia can be caused by a large loss of
blood. Some conditions that can result in blood loss include severe menstrual
bleeding, stomach ulcers, colon cancer,
inflammatory bowel disease, or a bladder
tumor.
Anemia can be caused by a decrease in red blood cell
production, reactions to some chemicals and medications, tumors,
Addison's disease, or by the absence of some essential
nutrient such as iron, folic acid, or vitamin
B12.
Anemia can also be caused by increased
destruction of red blood cells due to conditions such as
hemolytic anemia or
sickle cell disease.
Low MCV and MCHC values can indicate anemia
caused by a lack of iron,
thalassemia, lead poisoning, or long-term infection.
Certain chronic diseases (such as diabetes or arthritis) may cause low MCV and
MCHC values.
A low number of platelets can be caused by infection,
lack of vitamin B12or folic acid, severe internal
bleeding, some types of cancer,
systemic lupus erythematosus (SLE), leukemia, certain
conditions involving the
immune system (such as
idiopathic thrombocytopenic purpura), or conditions in
which the platelet count appears low because too many platelets are being
stored in the
spleen.
Abnormal size or structure of blood cells may mean
Red blood cells may be unusually large
(macrocytes) or small (microcytes). Macrocytes may indicate some types of
anemia, a liver problem, or a vitamin B12 or folic acid
deficiency. Microcytes may indicate iron deficiency, thalassemia, or lead
poisoning.
The red blood cells may have an abnormal shape.
Sickle-shaped cells may indicate
sickle cell anemia. Oval cells may indicate liver
disease or a
stomach ulcer.
The structures inside the
red blood cell may look abnormal. Some conditions that can cause an abnormal
appearance of red blood cells include
malaria,
lead poisoning, and some types of
anemia and
leukemia.
Medical online consultation with qualified doctors
Copyright © 2004-2005