Laboratory Tests Flashcards
Define Complete blood count
- aka as a complete blood cell count, full blood count (FBC), or full blood exam (FBE),
- a blood panelrequested by a doctor or other medical professional that gives information about the cells in a patient’s blood, such as the cell count for each cell type and the concentrations of various proteins and minerals.
- These commonly performed blood tests in medicine, can provide an overview of a patient’s general health status.
- A scientist or lab technician performs the requested testing and provides the requesting medical professional with the results of the CBC.
In what time frame was blood counts of various types have been used for clinical purposes? When was Automated equipment to carry out complete blood counts developed
- 19th century.
- 1950s and 1960s
What are three types of blood cell circulating the bloodstream?
- White blood cells (leukocytes), red blood cells (erythrocytes), and platelets (thrombocytes).
- Abnormally high or low counts may indicate the presence of many forms of disease,
When is CBC performed?
- Annual physical examinations i
Purpose of CBC?
screen for some diseases, to confirm a diagnosis of some medical conditions, to monitor a medical condition, and to monitor changes in the body caused by medical treatments.
Patient needing blood transfusion
For blood transfusion, a blood count may be used to get data which would help plan an amount of treatment.
In such cases, the person should have only one blood count for the day, and the transfusion of red blood cells or platelets should be planned based on that.
Multiple blood draws and counts throughout the day are an excessive use of phlebotomy and can lead to unnecessary additional transfusions, and the extra unnecessary treatment would be outside of medical guidelines
The procedure of CBC
- A phlebotomist collects the sample through venipuncture, drawing the blood into a test tube containing an anticoagulant (EDTA, sometimes citrate) to stop it from clotting.
- The sample is then transported to a laboratory. Sometimes the sample is drawn off a finger prick using a Pasteur pipette for immediate processing by an automated counter.
- In the past, counting the cells in a patient’s blood was performed manually, by viewing a slide prepared with a sample of the patient’s blood (a blood film, or peripheral smear) under a microscope. -LESS COMMON, automated analyzer used instead
- 10-20%examined manually
2 types of procedures for CBC
Automated and Manula
Automated CBC
Automated:
Most blood counts today include a CBC count and leukocyte differential count (LDC).
The blood is well mixed (though not shaken) and placed on a rack in the analyzer. This instrument has flow cells, photometers and apertures that analyze different elements in the blood.
The cell counting component counts the numbers and types of different cells within the blood. The results are printed out or sent to a computer for review. Results are precise as so many cells are counted.
The two main sensors used are light detectors and electrical impedance, measure the amount of hemoglobin in the blood and within each red blood cell. This is done by adding a diluent that lyses the cells which is then pumped into a spectro-photometric measuring cuvette. The change in color of the lysate equates to the hemoglobin content of the blood.
Manual CBC
- Hemocytometers (counting chambers that hold a specified volume of diluted blood and divide it with grid lines) are used to calculate the number of red and white cells per litre of blood.
- To identify the numbers of different white cells, a blood film is made, and a large number of white blood cells (at least 100) are counted
Manual vs Automated
- Manual counting is subject to sampling error because so few cells are counted compared with automated analysis. A manual count will also give information about other cells that are not normally present in peripheral blood, but may be released in certain disease processes.
- Although automated analysers give fast, reliable results regarding the number, average size, and variation in size of red blood cells, they do not detect cells’ shapes which manual does.
Types of white blood cells
- Neutrophils: May indicate bacterial infection and some viral infections
- Lymphocytes: Higher with some viral infections such as glandular fever.
- Monocytes: May be raised in bacterial infection, tuberculosis, malaria, Rocky Mountain spotted fever, monocytic leukemia, chronic ulcerative colitis and regional enteritis
- Eosinophils: Increased in parasitic infections, asthma, or allergic reaction.
- Basophils: May be increased in bone marrow related conditions such as leukemia or lymphoma.
Low red blood cells mean..and low hemoglobin means….
- Iron deficiency; anemia shows up as a Low RBC count
- Anemia.
Most common creatinine indicator of renal function
Serum creatinine is the most commonly used indicator of renal function
A rise in blood creatinine level is a late marker, observed only with marked damage to functioning nephrons. Therefore, this test is unsuitable for detecting early-stage kidney disease. A better estimation of kidney function is given by calculating the estimated glomerular filtration rate (eGFR). eGFR can be accurately calculated without a 24-hour urine collection using serum creatinine concentration and some or all of the following variables: sex, age, weight, and race, as suggested by the American Diabetes Association.
