L 4.1 Flashcards
Platelet Methodologies 1&2 (137 cards)
1
Q
What is the largest cell in the bone marrow?
A
Megakaryocyte
2
Q
What is another term for the mature megakaryocyte in some books?
A
Metamegakaryocyte
3
Q
What happens once the metamegakaryocyte matures?
A
Outer edges of cytoplasm break off into fragments that form the platelets/ thrombocytes
4
Q
What are the two distinctive areas observed in a Wright stained blood smear?
A
Granulomere/Chronomere (Chromomere) and Hyalomere
5
Q
what are the synonyms for granulomere? define.
A
Granulomere/ Chromomere/ Chronomere.
Central area filled with purplish granules
6
Q
define hyalomere
A
pale blue cytoplasm of platelet stained with wright stain
7
Q
What stain can be sued to demonstrate platelets?
A
Wright’s stain
8
Q
What is the lifespan of platelets in circulating blood (in vivo)?
A
8-11 days
9
Q
what is the lifespan of platelets in vitro?
A
24 hours/ 1 day
10
Q
Why is platelet concentration done with freshly drawn blood in blood banks?
A
Platelet lifespan less than 24 hours once blood is drawn
11
Q
What is the normal ratio of blood cells?
A
1 WBC: 600 RBC: 40 platelets
12
Q
What are the functions of platelets?
A
- Help in maintaining integrity of BV
- Help in primary hemostasis
- initiate clot retraction
13
Q
What is one function of platelets regarding blood vessels?
A
Help in maintaining integrity
14
Q
How do platelets help in maintaining BV integrity?
A
plts fill in gaps in the vascular endothelium, and helps in maintaining enough RBCs to circulate in BV
15
Q
What is the primary function of platelets in hemostasis?
A
Help in primary hemostasis
16
Q
What does platelets do in helping primary hemostasis?
A
- adhere to injured BV
- Aggregate at site of injury
- release biochemicals important to P. hemostasis
- source of factor 3 (tissue thromboplastin)
17
Q
Where does peripheral blood show a lower platelet count compared to arterial and venous blood?
A
After skin puncture
18
Q
Where does low platelet count manifest in menstruating women?
A
before menstruation and 1st day of menstruation
Why? cuz platelets prioritize going to site of injury/bleeding (the uterus). therefore low platelet count in blood
19
Q
Rank blood from highest platelet count to lowest platelet count among arterial, venous, peripheral blood
A
arterial > venous > peripheral blood
1 arterial
2. venous
3. peripheral
20
Q
why does peripheral blood have the lowest plt ct than venous and arterial?
A
peripheral blood is obtained from skin puncture, (since platelets have the ability to adhere to surfaces) plt tends to attach of the site of injury for hemostasis function, therefore lowering plt in blood
21
Q
What is one function of platelets that causes them to have a slightly lower count in peripheral blood?
A
Hemostasis
22
Q
Does lymph and other body fluids contain platelets?
A
No platelets present
23
Q
Platelet count is difficult to perform because of:
A
1, platelets are small
2. tend to disintegrate when in contact with air
3. tendency to form clumps with one another
4. ability to attach to glass and foreign surfaces
5. difficult to distinguish between dust, dirt and bacteria
6. not well distributed in circulation
24
Q
Why should glass or plain test tubes not be used for blood samples?
A
Platelets attach to the glass, causing false low platelet count.
25
specimens that can be used in plt ct.
venous blood and capillary blood
26
what is the recommended specimen for plt ct
venous blood
27
[venous blood]
collection container
storage/ satisfactory stability
recommended materials to use
concentration of EDTA tube
1. EDTA vacutainer tube
2. 5 hours @ RT (20-25C)
24 hhours @ Ref temp (4C)
3. siliconized plain vacutainer tube and plastic syringe
4. 1.5 +_ 0.25 mg per ml of blood (IDEAL: 1-2 mg per ml of blood)
28
What is the recommended concentration of EDTA in a tube for clinical diagnosis?
1 to 2 milligrams per ml of blood.
29
What happens if the concentration of EDTA in a tube exceeds 2 mg/ml of blood?
Platelets swell and fragment causing false high
30
[capillary blood]
site of puncture
free-flowing blood is ideal, but if not what to do?
order of draw
1. 3/4th finger of nondominant hand, perpendicular to the ridges of the fingerprint.
plantar surface of the heel
2. if flow is poor, massage finger
if necessary, do another puncture
3. platelet ct > other tests (smear, culture, anticoagulants, coagulants)
31
result when glass vacutainer tube and glass syringe is used. Why?
false (-) ; plt tend to attach to glass surfaces and foreign surfaces
32
dilution of blood to diluent in dameshek method
1:05
33
result when plt swell and fragment
false +
34
dameshek method is also called?
wet method for indirect platelet counting
35
[dameshek method]
What is the normal value of plt?
500,000-900,000 / uL or 500-900 x10^9 /L
36
[brecker and cronkite]
What is the normal value of plt?
150,000-400,000 / uL or 150-400 x10^9 /L
37
[fonio method]
What is the normal value of plt?
250,000-500,000 plt/ uL or 250-500 x10^9 /L
38
[rees-ecker]
What is the normal value of plt?
150,000-400,000 / uL or 150-400 x10^9 /L
39
[olef method] What is the normal value of plt?
437,000 - 586,000 plt/ul or 437 - 586x10^9/L
40
[brecker and cronkite] range of error
+= 8-10%
41
[rees-ecker] range of error
+/- 16-25%
42
What is Wet Mount?
Wet Method of Indirect Platelet Count or dameshek method
43
Why should counting be preferably done in the central area of a hemocytometer during RBC count?
RBCs tend to concentrate at the edges of the cover slip
44
what modification was made for modified damechek method?
usage of siliconized medicine dropper in diluting blood
45
What is the issue with the platelet to RBC ratio in the central area of a hemocytometer during RBC count?
Falsely high ratio
46
What is also called as the dry method
fonio method
47
How many R squares are inside the central big square?
25 R square
48
difference in focus in direct and indirect methods
indirect methods uses OIO
direct method uses HPO
49
[brecker and cronkite] allowable difference of number of platelets on each side
+/- 10 plt
50
How many R squares are needed for RBC count?
5
51
[brecker and cronkite]
How many R squares are needed for platelet count (1 chamber)? {2 chamber)?
10 R squares , 20 R squares
52
What is the area of the central big square in hemacytometer?
1sq. mm.
53
differentiate platelet results of brecker and cronkite from rees-ecker
brecker and cronkite - round to oval tiny glistening objects with irregular borders
rees- ecker - lilac colored tiny glistening objects
54
What is the area of 1 R square in hemacytometer??
1/25 sq. mm
55
what is the hemacytometer used?
spencer bright line double counting chamber with improved Neubauer ruling
56
progenitor of brecker and cronkite
rees-ecker method
57
[brecker and cronkite]
How many squares should form an X of R squares?
9
58
[T or F] For rees- ecker, blood is sucked to 1.0 ml and diluent is sucked to 101 mark
F,
Rees-ecker is sucked to 0.5 ml (blood) and diluent is sucked to 101 mark {giving 1:200 ratio)
Brecker and Cronkite is sucked to 1.0 ml (blood) and diluent is sucked to 101 mark {giving 1:100 ratio)
59
[brecker and cronkite] how many total r squares are counted for plt count
20 r squares (10 squares each chamber)
60
[rees-ecker] how many total r squares are counted for plt count
50 r squares (25 each chamber)
61
What to do if the number of platelets in 20 R squares is less than 100?
Add more squares until 100 platelets are recorded
62
What to do if the number of platelets in 50 R squares is less than 50?
redo test with 1:20 or 1:10 dilution using WBC pipette
63
What are the thrombocytes or platelets?
fragments f the outer edges of the megakaryocyte
64
What are not cells, but fragments of the cytoplasm of the mature megakaryocyte or metamegakaryocyte?
thrombocytes or platelets
65
What are very small compared to the red blood cells?
platelets
66
The platelets are very small compared to what type of cells?
red blood cells
67
Where do platelets or thrombocytes accumulate?
bone marrow
68
The platelets or thrombocytes are then swept into what?
bloodstream
69
[Morphology] Shade of smear is made from? Samples used to make smear.
Anticoagulated Blood and Capillary Blood
70
describe newly formed platelets in regards to: size, activity and homeostatic function
NEW: large, high activity and effective homeostatic function
71
What cell fragments are derived from?
cytoplasm of megakaryocyte
72
[morphology]
Describe platelets in capillary blood
- Have irregular borders [irregularity increases when time between pricking and smearing increases (increased border irregularity = increased time between pricking and smearing) ]
- Develops filopodia (thread-like structures that form a intertwined net to trap escaping blood) after pricking to help homeostasis
73
[morphology]
Describe platelets in anticoagulated blood
round, oval to rod-shape ; small
74
Fibrinogen is also needed for what?
platelet aggregation
75
What is needed for platelet aggregation?
ADP (adenosine diphosphate), Thromboxane (a2) plus fibrinogen
76
What type of aggregation is Fibrinogen needed for?
platelet aggregation
77
what biochemicals (with their purpose) are released for primary hemostasis?
1. serotonin - vasoconstrictor
2. ADP - plt aggregator
3. thromboxane - vasoconstrictor + plt aggregator
78
what factor is also needed for platelets to attach to the injured blood vessel?
von willebrand factor (Factor xvi)
79
What is the process by which serum is expressed from the clot?
Clot Retraction
80
What is a contractile protein in the platelets that help in clot retraction?
Thrombosthenin
81
What is thrombosthenin
contractile protein in platelets that help in expression of serum in clot
82
What is the name for the increase in platelets above normal?
Thrombocytosis
83
What is a decrease in number of platelets below normal?
Thrombocytopenia
84
platelet distribution in platelet count. explain
platelet count is 2/3 of the total plt mass. 1/3 is stored in the spleen (newly released plt from the bone marrow)
85
Physiological conditions/ normal variations for platelet count
1. spleen
2. neonates
3. menstruating women
4. arterial blood
5. venous blood
6. lymph and other body fluids
86
spleen is also called as the
platelet reservoir in man holding 1/3 of the total platelet mass
87
Release of spleenic pool can be triggered by
1. administration of epinephrine
2. variety of stresses
88
administration of epinephrine / adrenaline can be caused by
1. polycythemia vera [marked with thrombocytosis]
2. thrombocythemia [marked with thrombocytosis (1 million plt per micron)]
[lead to bleeding because of high consumption of plts due to thrombocytosis]
89
variety of stressors that can lead to release of spleenic pool
HES- HC
1. hypoxia
2. excitement
3. strenuous exercise
4. high altitude
5. cold temperatures
90
What is caused by the consumption of platelets?
bleeding
91
What does hypoxia cause from the spleen?
release of platelets
92
What causes release of platelets from the spleen (spleenic pool)?
hypoxia, excitement, strenuous exercise, high altitude, cold temperatures
93
What do those who want to do exercises in the gym have?
higher platelet count
94
[T or F] Adults have higher platelets than neonates
T
95
[T or F] Neonates have thrombocytopenia at birth
T
96
How many days does neonate's thrombocytopenia last?
first 4 days
97
[T or F] neonates have higher platelet count than adults
F. Neonates should have slightly lower plt ct than adults
98
What type of capillary blood puncture site has hair which favors adhesion of platelets?
earlobe
99
Give disadvantages of dameshek method
1. does not lyse rbcs and wbcs
2. stable only for 30 mins
100
What is the composition of Rees-Ecker diluent?
3.8 g sodium citrate
0.2 ml of 40% formaldehyde
0.1 g of brilliant cresyl blue
100 ml aqueous fluid
101
what are the indirect methods for platelet count?
Dameshek method
fonio method
olef method
102
What is the purpose of Na Citrate?
anticoagulant
103
what is the diluting fluid used in the dameshek method?
rees-ecker diluting fluid
104
platelet count methods
indirect and direct methods
105
How many drops of blood do 2 Wipe off?
1st
106
How do you let blood flow into the diluent?
Gently press the finger
107
How many minutes will allow the settling of the cells to last?
15 minutes
108
stability of result in dameshek method
30 mins
109
How many RBCs are recorded?
1,000
110
Result of platelets in Damesheck method?
lilac colored tiny glistening
111
How many fields did one book recommend to count platelets and RBCs?
four
112
what does it mean when clumps of platelets are found in your slide during examination/investigation?
inadequate mixing
113
What part of the smear does the counting of RBCs take in Fonio method?
1/5 ? 1/3 part from end of smear
114
fonio method is also called
dry method for indirect platelet counting
115
[fonio method] diluting fluid used
14% magnesium sulfate
116
What portion of the smear is well-distributed?
thin end portion
117
[fonio method] blood to diluent ratio
1:03
118
[T or F] In dameshek method, resulting fluid (Diluent + blood) is thicker than fonio.
False. Fonio is thicker than dameshek
119
Where are cells in the thin end portion of the smear?
well-distributed
120
What is a dry method?
Fonio method
121
Advantages of Fonio method (dry method)
1. easier to count platelets and RBC cuz it is fixed (Dried) and stained
2. size and shape is observed
122
What is the same principle as Dameshek and Fonio?
olef's method, but this method is more cumbersome
123
What stained blood smear is needed to counter check any procedure in the lab?
Wright?s stain
124
What does a platelet/OIF provide?
an estimation of platelet numbers, size, and distribution
125
[rees-ecker] ratio of blood to diluent
0.180555556
126
[brecker and cronkite] ratio of blood to diluent
0.111111111
127
[counter-shecking plt count results
a. <= 1/ OIF
b. 5-20/OIF
c. >25/OIF
d. 1 plt/ 10-30 RBC
a. <=1/ OIF = thrombocytopenia
b. 5-20/OIF = adequate plt/ normal condition
c. >25/OIF = thrombocytosis
d. 1 plt/ 10-30 RBC = adequate plt/ normal condition
128
what are the direct methods for platelet count?
method of brecker and cronkite (reference method), rees-ecker method, guy and leakes method
129
disadvantage of brecker and cronkite method
1. can lyse rbc but not wbc
2. stable for reading for 8 hours
130
how many pipettes are used for the modified method of rees-ecker?
1 pipetter for both chamber
131
What is the reference method?
BRECKER and CRONKITE METHOD
132
What type of methods are available for platelet count?
direct, indirect and electronic methods
133
how many pipettes are used for the reference method?
2 pipette, 1 per chamber
134
[brecker and cronkite] diluent used
1% ammonium oxalate
135
how is indirect and direct method for counting platelets different?
indirect method - counting of platelets are done simultaneously with RBCs. plt ct. is dependent on rbcs-
direct method - plts are counted directly on the hemacytometer (similar to rbcs and wbcs)
136
Microscope used in rees-ecker method and method by brecker and cronkite
1. rees-ecker - light microscope
2. method by brecker and cronkite - phase contrast microscope with green/gray filter, wherein:
green filter - platelets appear dark
gray filter - platelets appear pink/ purple
137
coverslip required for the reference method
no. 1 or 1 1/2 thick coverslip
