Transcript File

Lesson Objectives
Upon completion of this lesson,
students should be able to:
1.Define and spell the terms to learn for
this chapter.
2.List the components of blood, including
the liquid and cellular portions and
functions of each.
3.Describe causes and implications for
each of the blood tests discussed.
Lesson Objectives
Upon completion of this lesson,
students should be able to:
4.Discuss the variables that can affect the
accuracy of laboratory test results.
5.Explain how hematology is used to
diagnose and treat disease.
Lesson Objectives
Upon completion of this lesson,
students should be able to:
6.Identify frequently used blood and
blood chemistry tests and describe
proper patient preparation for each.
7.State the normal values for each of the
blood tests discussed and identify
critical values to report immediately.
Hematology
• The study of blood and the tissues
that produce it
• Lab tests performed on blood are
commonly used to verify or rule out
a suspected diagnosis.
• Blood analysis is one of the most
common diagnostic tools in the
doctor's office.
The Medical Assistant's Role
• MA collects the specimen
• MA may also perform laboratory
testing within his or her scope of
practice
• MA must know normal values and
understand what test results reveal
The Medical Assistant's Role
• Blood Specimen Collection
– Strictly regulated by OSHA
– Follow CDC standard precautions at all
times.
The Medical Assistant's Role
• Blood Specimen Collection
– Laboratories must adhere to CLIA
standards; MA must follow regulation
guidelines
– Refer to Chapter 47 regarding
equipment and procedures for blood
collection.
Blood Function, Formation, and
Components
• Main functions of the blood are
transportation and protection
– Blood takes oxygen and nutrients to the
body and removes carbon dioxide.
– Blood takes waste products to the
lungs, liver, kidneys, and skin for
elimination.
Blood Function, Formation,
and Components
• Main functions of the blood are
transportation and protection
– Blood carries white blood cells to help
fight off infection and contains platelets
to begin the healing process.
– Blood assists in regulating body
temperature.
Blood Function, Formation,
and Components
• Plasma
– Liquid component of blood
– Makes up about 55 % of the
composition of blood
– Carries blood cells and other substances
to the different parts of the body
Blood Function, Formation,
and Components
• Plasma
– Key component of plasma is fibrinogen
– Serum is plasma without the fibrinogen.
– 99% of plasma is water; the other 10 %
is solid substances that dissolve in the
plasma.
Blood Function, Formation,
and Components
• Cellular Components (Formed
Elements)
– The formation of blood cells is called
hematopoiesis.
– Blood cells originate from the
hematopoietic stem cell, but mature
into one of seven individual types of
cells.
Critical Thinking Question
1.Where does hematopoiesis primarily
occur in adults?
Blood Function, Formation,
and Components
• Red blood cells (erythrocytes)
– Transportation of oxygen and carbon
dioxide
Blood Function, Formation,
and Components
• White blood cells (leukocytes)
– Defense – five types:
• Granular leukocytes
– Neutrophils
– Eosinophils
– Basophils
Blood Function, Formation,
and Components
• White blood cells (leukocytes)
– Defense – five types:
• Nongranular leukocytes
– Lymphocytes
– Monocytes
Blood Function, Formation,
and Components
• Platelets (thrombocytes)
– Clotting
– Although hematopoiesis occurs primarily
in the bone marrow of the adult,
lymphocytes are also produced in the
lymph nodes.
Formed Elements and
Associated Tests
• Blood tests ordered individually or in
groups
– Referred to as panels, profiles, or counts
Formed Elements and
Associated Tests
• CBC is one of the most common
combinations of tests routinely
ordered
– Includes red blood cell (RBC) counts,
RBC indices, hemoglobin (Hgb),
hematocrit (Hct), white blood cell (WBC)
counts (with or without differential),
platelet counts, and blood cell
morphology
Formed Elements and
Associated Tests
• Red Blood Cells and Red Blood Cell
Tests
– (RBCs) or erythrocytes: vessels that
carry hemoglobin throughout the body.
Formed Elements and
Associated Tests
• Red Blood Cells and Red Blood Cell
Tests
– Hemoglobin
• A vital protein molecule found in red blood
cells that has two primary functions
• Carry oxygen from lungs to cells of the body
Formed Elements and
Associated Tests
• Red Blood Cells and Red Blood Cell
Tests
– Hemoglobin
• Carry carbon dioxide from throughout the
body back to the lungs where it can be
expelled with exhalation
FIGURE 48-2 Red cells
have a biconcave shape.
Formed Elements and
Associated Tests
• Erythrocyte or Red Blood Cell (RBC)
Count
– RBC count is the number of red blood
cells per cubic millimeter (mm3) of
blood
Formed Elements and
Associated Tests
• Erythrocyte or Red Blood Cell (RBC)
Count
– Normal values vary according to age
and gender
• Normal RBC range for a male adult is 4.5 to
6 million/mm3
• Normal female RBC range is 4 to 5.5
million/mm3, although it may slightly
decrease during pregnancy
Formed Elements and
Associated Tests
• Erythrocyte or Red Blood Cell (RBC)
Count
– Formation of RBCs is controlled
somewhat by erythropoietin
– Erythropoietin secreted by the kidneys
in an adult and by the liver in a fetus
Formed Elements and
Associated Tests
• Erythrocyte or Red Blood Cell (RBC)
Count
– Hypoxemia
• The kidneys typically compensate by
secreting extra erythropoietin, which in turn
stimulates the bone marrow to produce
more red blood cells
Formed Elements and
Associated Tests
• Erythrocyte or Red Blood Cell (RBC)
Count
– Anemia
• A condition in which the blood has a lower
than normal level of red blood cells or of
hemoglobin within the red blood cells
Formed Elements and
Associated Tests
• Erythrocyte or Red Blood Cell (RBC)
Count
– Polycythemia
• A condition in which the blood has a higher
than normal level of red blood cells
Formed Elements and
Associated Tests
• Erythrocyte or Red Blood Cell (RBC)
Count
– Manual RBC count requires small
samples of the blood specimen to be
diluted in a special solution, which is
added to hemocytometer
Formed Elements and
Associated Tests
• Erythrocyte or Red Blood Cell (RBC)
Count
– Hemocytometer is placed on a
microscope used to count the cells
– Test is not considered CLIA-waived
– More specific training is required before
MA can perform this test in a medical
laboratory.
Formed Elements and
Associated Tests
• Reticulocyte Count
– The percentage of reticulocytes in the
blood in relation to the number of
mature RBCs
– RBCs last for about four months and are
continuously being reproduced in the
body
– Reticulocytes generally mature within 48
hours.
Formed Elements and
Associated Tests
• Reticulocyte Count
– Helps to determine the ability of the
bone marrow to compensate for RBC
loss
– Often used to monitor the response to
treatment for anemia
Formed Elements and
Associated Tests
• Reticulocyte Count
– Increased rates typical in pregnancy,
newborns, high altitudes, and
stimulated red blood cell production
– Decreased reticulocytes noted in renal
or bone marrow disease, use of certain
drugs, aplastic anemia, alcoholism, folic
acid deficiency, and transfusions
Formed Elements and
Associated Tests
• Hemoglobin (Hgb)
– Red blood cells contain hemoglobin
– Consists of iron (heme) and a protein
(globulin)
– Hemoglobin in the blood is responsible
for carrying oxygen throughout the
body.
Formed Elements and
Associated Tests
• Hemoglobin (Hgb)
– Higher Hgb levels
• The body is able to transport more oxygen
– Lower levels
• Less oxygen is in circulation
– Normal values for adult females are 12–
16 g/dL and for males 14–18 g/dL.
Formed Elements and
Associated Tests
• Hemoglobin (Hgb)
– Measured by an automated blood
analyzer or manually by a
hemoglobinometer
– Manual calculations are not CLIAwaived.
Formed Elements and
Associated Tests
• Hemoglobin (Hgb)
– Values can be determined by the
specific gravity method or the
cyanmethemoglobin method.
– Abnormal levels can be dangerous
because they affect the level of oxygen
available to the cells.
FIGURE 48-4
Hemoglobinometer (manual
blood analyzer).
FIGURE 48-5 Automated
blood analyzer.
Nicram Sabod/Shutterstock
Formed Elements and
Associated Tests
• Hemoglobin (Hgb)
– Hemolytic disorders, cancers, anemias,
sickle cell disease, thalassemia,
frequent blood draws or loss, fluid
retention, and pregnancy can lower Hgb
levels
– Hgb less than 5 g/dL is considered to be
a critical value; report to physician
immediately
Formed Elements and
Associated Tests
• Hemoglobin (Hgb)
– Hgb over 20 g/dLo can lead to blood
clots from increased concentration;
considered critical
Determining Hemoglobin
Using the
Hemoglobinometer
• Refer to Procedure 48-1 in the
student text for detailed instructions
in this technique.
– Note: This test is typically not
performed by a medical assistant in a
medical office setting.
Formed Elements and
Associated Tests
• Hematocrit (Hct)
– Hct test evaluates the percentage of
packed red blood cells in the total
volume of blood
– In a patient with normal RBC and Hgb
levels, the approximate hematocrit
should be about three times the
hemoglobin level.
• Normal hematocrit is 40 to 50 % in males
and 35 to 45 % in females
Formed Elements and
Associated Tests
• Hematocrit (Hct)
– Low hematocrit may indicate anemia or
hemorrhage.
– Elevated hematocrit may indicate
dehydration or polycythemia.
Formed Elements and
Associated Tests
• Hematocrit (Hct)
– High glucose levels may falsely indicate
elevated hematocrit levels.
– The microhematocrit, or "crit," is a
hematocrit performed on an extremely
small quantity of blood collected in a
capillary tube.
FIGURE 48-7 The
hematocrit.
FIGURE 48-8
Hematocrits, left to right:
normal, anemia,
polycythemia.
FIGURE 48-9 A
microhematocrit.
Performing a
Microhematocrit
1.Perform hand hygiene and apply
gloves.
2.Assemble equipment.
3.Fill two capillary tubes threequarters full. The blood specimen can
be obtained from a vacuum tube of
anticoagulated blood using a plain
capillary tube or directly from a
finger-stick site using a heparinized
capillary tube. Seal one end in the
Performing a
Microhematocrit
FIGURE A Centrifuge and
supplies.
Performing a
Microhematocrit
4.Place capillary tubes in the
centrifuge with the sealed ends
against the rubber gasket. If more
than one patient's blood is being
tested, mark down the number of
the slot the patient's tube is in. Spin
for three to five minutes at 10,000
rpm. (Always check the
manufacturer's recommendations for
proper time and speed.) After
(continued) Performing a
Microhematocrit
FIGURE B Loading a
centrifuge.
Suthep/Shutterstock
Performing a
Microhematocrit
5.Remove tubes immediately after
centrifuge stops. If tubes are not
removed immediately, blood may
begin to mix together.
Performing a
Microhematocrit
6.Determine the results. Use the Hct
card by placing the sealing clay just
below the zero line on both tubes.
Then, on both tubes, match the top
of the plasma with the 100 line. Read
results on both tubes directly below
the buffy coat. Then add those
results together and divide by 2.
Performing a
Microhematocrit
7.Discard the tubes into the sharps
container
8.Remove gloves and perform hand
hygiene
9.Record the value as a percentage on
the patient's medical record.
Formed Elements and
Associated Tests
• Erythrocyte/RBC Indices
– Help to differentiate the type of anemia
present by indicating the size of RBCs
and the concentration of Hgb
– Mean corpuscular volume (MCV)
measures the average size of RBCs and
classifies them according to size
– Mean corpuscular hemoglobin (MCH)
measures the average amount of
hemoglobin in a red blood cell
Formed Elements and
Associated Tests
• Erythrocyte/RBC Indices
– Mean corpuscular hemoglobin
concentration (MCHC) measures the
amount of hemoglobin relative to the
size of the cell
– When MCV, MCH, and MCHC are
decreased, iron deficiency anemia is
likely
Formed Elements and
Associated Tests
• Erythrocyte/RBC Indices
– When MCV, MCH, and MCHC are
increased, vitamin B12 or folic acid
deficiency is likely
Formed Elements and
Associated Tests
• Erythrocyte Sedimentation Rate
(ESR)
– Also called "sed rate"
– Evaluates red blood cells
– Determines the rate at which RBCs
settle at the bottom of a tube
Formed Elements and
Associated Tests
• Erythrocyte Sedimentation Rate
(ESR)
– Related to the condition of the RBCs and
the amount of fibrinogen in the plasma
– RBCs that fall at a faster than normal
rate can indicate the possible existence
of conditions associated with increased
fibrinogen.
Formed Elements and
Associated Tests
• Erythrocyte Sedimentation Rate
(ESR)
– Not diagnostic; used in conjunction with
other tests to determine a diagnosis
– Done using either the Wintrobe or the
Westergren method
Formed Elements and
Associated Tests
• Erythrocyte Sedimentation Rate
(ESR)
– Increased values may suggest
inflammation.
– ESR may also be elevated because of
menstruation, pregnancy, and the use of
specific medications.
Performing an ESR Test
Using the Wintrobe Tube
Method
1.Perform hand hygiene and apply
gloves.
2.Assemble equipment.
3.Obtain a whole-blood sample using a
purple-top tube. Mix well. EDTA is
the anticoagulant of choice.
4.Slowly fill Wintrobe tube with blood.
Avoid air bubbles.
Performing an ESR Test
Using the Wintrobe Tube
Method
5.Adjust the meniscus of the specimen
to the zero line at the top of the
tube.
6.Maintain the tube in an upright
vertical position for one hour.
Performing an ESR Test
Using the Wintrobe Tube
Method
7.After one hour, record the number of
RBCs that settle. Read the ESR on
the same side of the tube as the zero
line at the top.
8.Remove gloves and perform hand
hygiene.
9.Record the procedure on the
patient's medical record.