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Blood Panel Review|
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Blood Composition
The average size person has approximately 5 to 6 liters of blood circulating at all times. Of
this, 45% consists of red blood cells, 55% plasma, and less than 1% white blood cells and
platelets.
Blood Groups and Type
Blood grouping is based on the specific types of antigens present on the red blood cell's
membranes. Blood groups are classified as A, B, AB, or O. The O group lacks antigens completely and is
often referred to as the universal donor.
The Rh Factor
Blood types are based on an additional antigen's presence in the blood. The Rh-positive person
has the antigen, while the Rh-negative person lacks it. This Rh-factor plays an important role during
pregnancy when the mother is Rh-negative and the child is Rh-positive. If the mother is not treated with
RhoGAM, her body will recognize the fetus as foreign and destroy it by developing antibodies against
it.
Organs and Structures Connected with BloodHeart - Propels blood, maintains blood pressureBlood vessels - Distribute blood around the bodyArteries Carry blood away from the heartCapillaries Site of diffusion between blood and interstitial fluids
Bone marrow - Primary site of cell productionLymphatic vessels - Carry lymph peripheral tissues to the veinsLymph nodes - Monitor composition of lymph, engulf pathogens, stimulate immune responseSpleen - Monitors circulating blood, engulfs pathogens, stimulates immune response; maintains body's reservoir for emergency blood supplyThymus - Controls development and maintenance of lymphocytesRBCs - Transport oxygen and carbon dioxide; cellular respirationWBCs - Defense mechanismPlasma - Liquid portion of blood responsible for carrying nutrients and water throughout bodyImmunoglobulins - Specific response to specific pathogens; also known as antibodiesPlatelets - Granules which aid in the initial clotting response of bloodFibrinogen - Protein in the bloodstream which forms small fibrin strands to close wounds when stimulated by thrombinProthrombin - Chemical substance which reacts with calcium to form thrombin; aids in clotting process
Clinical laboratory testing
Clinical laboratory testing plays a crucial role in the detection, diagnosis, and treatment of
disease! There are numerous different types of blood tests performed in a medical office to identify
conditions inside the body. Many blood tests are part of a routine medical examination or monitor disease
processes and progress of treatments. The complete blood count (CBC) is one of the most common blood tests
performed in the medical office, clinic, or hospital and is part of the blood panel.
The medically trained technician must be able to obtain a blood sample that best reflects the
body's condition at the time the collection was made. This condition must be preserved inside the test
tube until the specimen can be tested. Certain hematology samples must remain thoroughly mixed prior to
testing. This is achieved by an automated blood rocker which can hold a number of tubes.
REMEMBER: Strict care of all specimens should be maintained throughout the process because
they represent the patient!
The Blood Cells
In a CBC, various types of hematic (blood) cells are analyzed, using six different tests on
whole blood:
Red blood cell count (RBC)
Hematocrit
Hemoglobin
White blood cell count (WBC)
Differential blood count (Diff)
Platelet count
The blood panel is an important set of tests to determine if a person is ill.
The blood panel gives the physician an indication of a patient's internal health, however, if a
patient's values falls outside of the range for this lab, it does not necessarily mean there is something
wrong with that patient on that specific test. The doctor will follow the blood panel over a certain
period to see which direction the trends are following. It is, however, important to understand that blood
panels are not relied on by themselves whether a patient is healthy or sick; the doctor uses
all of the information available in regards to the diagnostic process, such as a urine
analysis, radiographs (x-rays), physical exam as well as the patient history.
The first part of the blood panel is called a CBC.
CBC stands for complete blood count and is a measure of a patient's white blood cells (WBC's) and
red blood cells (RBC's). RBC's are the most common type of blood cell and are responsible for transporting
oxygen throughout the body.
In measuring the RBC`s the doctor is looking for a low count, called anemia, and a high
count, called polycythemia. Of the two, anemia is much more common. It is important to understand
that anemia is not a disease, but rather it is a potential sign of a disease. Low numbers in RBCs may also
indicate bone marrow failure, leukemia, and external or internal bleeding (hemorrhage.)
The RBC's are measured with three different tests, which are the
RBC number
hematocrit (HCT)
hemoglobin (Hg)
The RBC's are counted with a machine that gives you an actual number, usually in the millions per
uL (uL is a millionth of a liter). For adult males this would be 4.7 to 6.1 million/uL, and for adult
females 4.2 to 5.4 million red cells per microliter (uL) of blood.
Hematocrit is a percent of the red blood cells in the serum and usuallyranges
between40% - 54% in males and 37% - 47% in females.
A low hematocrit may indicate various types of anemia, blood loss, bone marrow failure, hemolysis
related to transfusion reaction, leukemia. malnutrition or specific nutritional deficiency, over
hydration, and rheumatoid arthritis. High hematocrit may indicate dehydration, burns, diarrhea, eclampsia,
erythrocytosis, polycythemia vera, and shock.
In the hematocrit test:
A small blood sample is obtained from the patient's finger tip
A very narrow capillary tube is used to draw up a drop of blood
The tube placed into a centrifuge which spins it at high speed
When a sample of blood is spun in a centrifuge, the cells and cell fragments are
separated from the liquid
The formed elements which are heavier than the liquid matrix are packed in the bottom of
the tube by the centrifugal force
Hemoglobin is the protein molecule in red blood cells that carries oxygen from the
lungs to the body's tissues and returns carbon dioxide from the tissues to the lungs. The iron contained
in hemoglobin is responsible for the red color of blood. Several methods exist for measuring hemoglobin,
most of which are done currently by automated machines designed to perform several different tests on
blood. Within the machine, the red blood cells are broken down to get the hemoglobin into a solution. The
free hemoglobin is exposed to a chemical containing cyanide which binds tightly with the hemoglobin
molecule to form cyanmethemoglobin. By shining a light through the solution and measuring how much light
is absorbed, the amount of hemoglobin can be determined.
The normal ranges for hemoglobin depend on the age and, beginning in adolescence, the sex of
the person. The normal ranges are:
Newborns: 17-22 gm/dl (dL, a tenth of a liter)
One (1) week of age: 15-20 gm/dl
One (1) month of age: 11-15 gm/dl
Children: 11-13 gm/dl
Adult males: 14-18 gm/dl
Adult women: 12-16 gm/dl
Men after middle age: 12.4-14.9 gm/dl
Women after middle age: 11.7-13.8 gm/dl
REMEMBER: All of these values may vary slightly between laboratories. Each
individual lab (or reference lab) has its own set of normal values!
Some laboratories do not differentiate between adult and "after middle age" hemoglobin
values.
All three values above combined are used in a determination of anemia. If anemia is present,
other tests are used to determine if the anemia is regenerative or non-regenerative. In regenerative
anemia's the body is making more red blood cells to make up for the anemia, in non-regenerative it is not.
This is an important point from the diagnostic point of view because certain diseases tend to be one or
the other.
The other part of the CBC is the analysis of the number and type of white blood
cells.
The total number of WBC's are noted, giving the doctor an overall indication if a problem might
exist and is closely tied to the immune system. A high WBC is termed leukocytosis. Inflammation,
infection, leukemia, or other cancers can cause an elevated WBC count. A low WBC count is called
leucopenia. A virus, an immunosuppressive disease, or a problem with the bone marrow can cause
it.
The white blood cell count is done by counting the number of white blood cells in a sample of
blood. A normal WBC is in the range of 4.8 to 10.8 thousand cells per microliter (uL) of blood. After the
total WBC is determined, the WBC's are broken down into their different types. This is called a
differential blood count or Diff.
There are five different types of white blood cells:
Neutrophils
Lymphocytes
Monocytes
Eosinophils
Basophils
These different types all have unique functions in the normal processes of the body. Changes in
the amounts of these different types, whether or not the WBC count is normal, high, or low, also gives the
doctor important information.
Histology Lessons -- LUMEN Histology home page
Normal Ranges for a Differential Blood Count:
Neutrophils: 3150 to 6200/uL*
Lymphocytes: 1500 to 3000/uL
Monocytes: 300 to 500/uL
Eosinophils: 50 to 250/uL
Basophils: 15 to 50/uL
*(/uL stands for per microliter of blood)
A high neutrophil count can indicate infection, certain types of cancer, arthritis, or physical
stress to the body, such as surgery, trauma or a heart attack. Low lymphocyte count can be a symptom of
AIDS. High monocyte count can indicate infection, often by bacteria. High eosinophil count can indicate
allergies, certain skin diseases, or parasitic infection. Immature white blood cells of any type can
indicate bacterial infection or leukemia.
In addition to the red and white blood cells the blood also contains platelets. Platelets
are the cell fragments essential for the process of blood clotting. A normal platelet count is 150 to 450
thousand platelets per microliter of blood. A low platelet count is called thrombocytopenia, which
may occur as a result of cancer treatment, certain leukemias, certain other types of cancer, or immune
thrombocytopenic purpura. Immune thrombocytopenic purpura is a disorder of the blood in which platelet
counts are abnormally low.
A platelet count may also be performed if a patient is about to undergo surgery.
MedicineNet.com
The Next Part of The Blood Panel Is The Chemistry Panel
The blood chemistry panel is also called the chem panel or biochemistry panel (bcp). Instead of
focusing on the white and red blood cells, the focus lies on the internal organs such as the liver, heart,
and kidneys and many biological functions via automated analyzers. Although the chem panel might be
ordered, it might be useless in determining whether a patient has a disease or not. Although normal chem
panel is highly advantageous it is no guarantee that a patient is healthy!
A good example of this is the kidney function test called BUN (blood urea
nitrogen).
This test is critical in diagnosing kidney problems in patients.
The chem panel also checks the general health of the body by measuring values such as protein,
glucose, and calcium and other chemical substances that are released from various tissues in the body. The
amounts of these chemicals in the blood may reflect abnormalities in the tissues secreting them.
Interpretation of problems in the chem panel is very complex, and must be interpreted in conjunction with
the other parameters of the diagnostic process.
A typical blood chemistry panel might include the following tests:
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General Metabolism
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Kidney Function
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Liver Function
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Thyroid
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Pancreas
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GLU (Glucose)
LDH (Lactate dehydrogenase)
CPK (Creatine phosphokinase)
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BUN (Blood Urea Nitrogen)
CREAT (Creatinine)
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Na (Sodium)
K (Potassium)
Cl (Chloride)
CA (Calcium)
PHOS (Phosphorus)
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ALP (Alkaline phosphatase)
ALT (Alanyl amino transferase)
ALB (Albumin)
GGT (Gamma-glutamyl transpeptidase)
SGPT (Serum glutamate pyruvate transaminase)
TP (Total Protein)
CHOL (Cholesterol)
GLOB (Globulin)
TBILI (Total Bilirubin)
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T3 (Triiodothyronine)
T4 (Thyroxine)
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AMY (Amylase)
LIP (Lipase)
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National Institute of Health All Panel Tests
In preparing patients for an operation the following blood test determine whether
the patient is fit to stand the effects of general anesthesia and surgery:
Red blood cells (RBC's) to check for anemia, proper oxygen carrying capacity
of the red blood cells, and adequate clotting
White blood cells (WBC's) to look for signs of infection, inflammation, or cancer
A protein test to check for dehydration, overall health status, and to help assess the
liver
A specific kidney test to check for proper kidney function
A specific liver test to check for proper liver function
Venipuncture
To obtain the blood specimens necessary for the above tests, the medical assistant or
phlebotomist performs a venipuncture usually on the arm, using a hollow bore needle with a syringe or
evacuated blood collection tubes (Vacutainer® systems.) Needles for venipuncture come in many
gauges and lengths. Routine venipuncture needles range from 20 -23 gauge, and 1-2 inches in length. When
selecting the right size of a needle the size of the vein, patient age, the amount of blood needed, and
personal preference are considered. All needles are sterile, for one time use only, and discarded directly
in the sharps container without recapping!
When obtaining a venous blood sample, the only risks to the patient are localized pain, hematoma
(accumulation of blood under the skin), bleeding, secondary infection and fainting in susceptible
individuals. The risk involved to the phlebotomist is accidental injury with the needle, also called
accidental finger-stick.
After successful collection of venous blood with a syringe, the blood is transferred into
separate test tubes for analysis. These test tubes have color coded tops or stoppers according to their
specific use.
Microcollection
Whenever only a small amount of blood is needed, it can easily be obtained using a lancet and
slender glass or plastic blood collection tubes to draw capillary blood from the finger or earlobe from a
young child from a weak adult, or from the heel of an infant under six months of age. Finger sticks hurt
more than venipunctures because there are more pain receptors in the finger tips than in the antecubital
area, however they are the preferred method in the situations just mentioned.
The risk involved for the person who handles these slender, fragile capillary blood collection
tubes is accidental breakage. Accidental breakage has been reported when the tubes were inserted into
putty to be sealed and during centrifugation. Breakage of the tubes during putty insertion may result in a
penetrating wound and blood inoculation to the user. Such injuries carry a risk of the transmission of
human immunodeficiency virus (HIV) and other bloodborne pathogens, such as HBV and HCV. Glass capillary
tubes can also break during centrifugation and cause blood to splatter, potentially exposing personnel to
bloodborne pathogens through mucous membranes or if the broken glass fragments injure the user, a
percutaneous exposure to blood.
To reduce the risk of injury due to breakage of capillary tubes, FDA, NIOSH, and OSHA
recommend that users consider blood collection devices less prone to accidental breakage,
including:
Capillary tubes that are not made of glass,
Glass capillary tubes wrapped in puncture-resistant film,
Products that use a method of sealing that does not require manually pushing one end of
the tube
into putty to form a plug, or
Products that allow the blood hematocrit to be measured without centrifugation.
Although FDA, NIOSH, and OSHA cannot recommend specific products, blood-collection devices with
these characteristics are currently available, and their use may reduce the risk of injury and blood
exposure.
The coating of the inside of the capillary tube is dependent on the type of sample being
collected, and for this reason the tubes are clearly identifiable by the color code. When one end of the
capillary tube touches the drop of blood it flows up into the tube via capillary effect as long as the
other end of the tube remains open. Close off the tube bore with the tip of the finger to prevent
gravitational drainage of the sample from the tube.
OSHA: Self-Sealing Capillary Tubes
Lancets
There are many lancets available. It is very important to use the correct lancet. There is a
linear relationship between the volume of the blood sample and the depth of the puncture. Shorter lancets
should to be used for capillary blood collection from neonates and children (1.0 mm, 1.5 mm, 2.0 mm) for
the respective capillary blood collection from finger or heel. Semiautomated units are preferred because
they will puncture the skin at a uniform depth. Adult lancets are 2.4 mm.
Vacuette - Components
Factors Affecting Blood Test Results
Patient is ill
Patient is injured
Patient is fasting
Patient is dehydrated
Patient is medicated (timing)
(ex. Insulin or thyroid medication)
Rough handling of sample *shaking causes hemolysis
Preservation, storage, and time until sent to lab
Specimen Labeling
ALL SPECIMEN CONTAINERS must be LABELED with the PATIENT'S NAME,
MEDICAL RECORD NUMBER, PATIENT NUMBER, DATE and INITIALS. Specimens not properly
labeled are NOT accepted by the laboratory.
Labeling the specimen container is the responsibility of the person
obtaining the specimen.
Specimens MUST be properly identified by checking the NAME and MEDICAL
RECORD NUMBER on the PATIENT'S WRIST BAND against the NAME and MEDICAL
RECORD NUMBER on the LABEL.
The blood specimens are properly labeled and packaged and analyzed at point-of-service or sent to
an outside reference laboratory to be analyzed by advanced laboratory equipment. The results of any blood
panel submitted to an out-side lab are usually faxed back to the medical office within 12-24 hours.
Example of A Hematology Analyzer Machine
Hematology Analyzers in a Cancer Center
Rapid Specimen Testing In the Medical Office
Over the past few years, the new health care system and managed care have affected patients by
restricting many of their health decisions and physicians on how they treat their patients. With new
regulations and new technology rapid or point-of-care (POC) diagnostic testing has more and more become
the norm. Many diagnostic screening tests are now performed right in the medical office at the day of the
appointment.
These laboratories are regulated under the
CLIA Program and maintain a high level of quality control by using highly automated and advanced
laboratory equipment. Most of the reagents, kits, and instruments used for screening in a medical office
are merely meant to substantiate a patient's condition. Any test results that are not within a normal
range must be sent to a reference laboratory for confirmation of the results.
REMEBER: Some of the point of care type analyzations may not be
as accurate as tests done by an outside reference laboratory.
The last decade has seen an increased utilization of in-house (in-clinic) chemistry and
hematology analyzers as well as an increase in the POC (point-of-care) type analyzers used in emergency
medicine. With this increased utilization comes additional responsibility. It is up to the practitioner
providing this laboratory service to assure that the service is going to benefit the patient. The
practitioner has the sole responsibility of quality assurance. This is especially important in North
America where no regulations exist to govern the manufacturer of instruments for veterinary laboratory
testing (or laboratories testing animal specimens).
Benefits and Disadvantages of Rapid Testing
As with any relatively complex issue, there are both pro's and con's to the widespread use of
rapid tests. The advantages include:
Rapid tests can provide clinicians timely information to guide patient management
Rapid tests can also be more convenient for clients, thus expediting counseling
to
patients in a variety of clinical and public health settings
Rapid tests using finger-stick blood and oral fluids could be administered by
professionals in non-clinical settings bringing testing results to hard to reach,
high-risk clients,
and facilitating access to other prevention services.
While laboratory tests are expensive and may take up to 24 to 48 hours to generate
results
Rapid screening kits and instruments can provide the physician with immediate
information
Required to take appropriate action with medication or other modalities of
treatment
CLIA Home Page - Clinical Laboratory Improvement Amendments
Errors and Pitfalls Associated with Clinical Analyzers
Diagnostic Reagent Kits
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