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Hema > L 4.1 > Flashcards

L 4.1 Flashcards

Platelet Methodologies 1&2

1
Q

What is the largest cell in the bone marrow?

A

Megakaryocyte

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2
Q

What is another term for the mature megakaryocyte in some books?

A

Metamegakaryocyte

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3
Q

What happens once the metamegakaryocyte matures?

A

Outer edges of cytoplasm break off into fragments that form the platelets/ thrombocytes

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4
Q

What are the two distinctive areas observed in a Wright stained blood smear?

A

Granulomere/Chronomere (Chromomere) and Hyalomere

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5
Q

what are the synonyms for granulomere? define.

A

Granulomere/ Chromomere/ Chronomere.
Central area filled with purplish granules

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6
Q

define hyalomere

A

pale blue cytoplasm of platelet stained with wright stain

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7
Q

What stain can be sued to demonstrate platelets?

A

Wright’s stain

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8
Q

What is the lifespan of platelets in circulating blood (in vivo)?

A

8-11 days

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9
Q

what is the lifespan of platelets in vitro?

A

24 hours/ 1 day

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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

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11
Q

What is the normal ratio of blood cells?

A

1 WBC: 600 RBC: 40 platelets

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12
Q

What are the functions of platelets?

A
  1. Help in maintaining integrity of BV
  2. Help in primary hemostasis
  3. initiate clot retraction
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13
Q

What is one function of platelets regarding blood vessels?

A

Help in maintaining integrity

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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

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15
Q

What is the primary function of platelets in hemostasis?

A

Help in primary hemostasis

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16
Q

What does platelets do in helping primary hemostasis?

A
  1. adhere to injured BV
  2. Aggregate at site of injury
  3. release biochemicals important to P. hemostasis
  4. source of factor 3 (tissue thromboplastin)
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17
Q

Where does peripheral blood show a lower platelet count compared to arterial and venous blood?

A

After skin puncture

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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

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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

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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

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21
Q

What is one function of platelets that causes them to have a slightly lower count in peripheral blood?

A

Hemostasis

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22
Q

Does lymph and other body fluids contain platelets?

A

No platelets present

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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

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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.

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25
Q

specimens that can be used in plt ct.

A

venous blood and capillary blood

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26
Q

what is the recommended specimen for plt ct

A

venous blood

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27
Q

[venous blood]
collection container
storage/ satisfactory stability
recommended materials to use
concentration of EDTA tube

A
  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)
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28
Q

What is the recommended concentration of EDTA in a tube for clinical diagnosis?

A

1 to 2 milligrams per ml of blood.

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29
Q

What happens if the concentration of EDTA in a tube exceeds 2 mg/ml of blood?

A

Platelets swell and fragment causing false high

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30
Q

[capillary blood]
site of puncture
free-flowing blood is ideal, but if not what to do?
order of draw

A
  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)
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31
Q

result when glass vacutainer tube and glass syringe is used. Why?

A

false (-) ; plt tend to attach to glass surfaces and foreign surfaces

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32
Q

dilution of blood to diluent in dameshek method

A

1:05

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33
Q

result when plt swell and fragment

A

false +

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34
Q

dameshek method is also called?

A

wet method for indirect platelet counting

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35
Q

[dameshek method]
What is the normal value of plt?

A

500,000-900,000 / uL or 500-900 x10^9 /L

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36
Q

[brecker and cronkite]
What is the normal value of plt?

A

150,000-400,000 / uL or 150-400 x10^9 /L

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37
Q

[fonio method]
What is the normal value of plt?

A

250,000-500,000 plt/ uL or 250-500 x10^9 /L

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38
Q

[rees-ecker]
What is the normal value of plt?

A

150,000-400,000 / uL or 150-400 x10^9 /L

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39
Q

[olef method] What is the normal value of plt?

A

437,000 - 586,000 plt/ul or 437 - 586x10^9/L

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40
Q

[brecker and cronkite] range of error

A

+= 8-10%

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41
Q

[rees-ecker] range of error

A

+/- 16-25%

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42
Q

What is Wet Mount?

A

Wet Method of Indirect Platelet Count or dameshek method

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43
Q

Why should counting be preferably done in the central area of a hemocytometer during RBC count?

A

RBCs tend to concentrate at the edges of the cover slip

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44
Q

what modification was made for modified damechek method?

A

usage of siliconized medicine dropper in diluting blood

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45
Q

What is the issue with the platelet to RBC ratio in the central area of a hemocytometer during RBC count?

A

Falsely high ratio

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46
Q

What is also called as the dry method

A

fonio method

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47
Q

How many R squares are inside the central big square?

A

25 R square

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48
Q

difference in focus in direct and indirect methods

A

indirect methods uses OIO
direct method uses HPO

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49
Q

[brecker and cronkite] allowable difference of number of platelets on each side

A

+/- 10 plt

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50
Q

How many R squares are needed for RBC count?

A

5

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51
Q

[brecker and cronkite]
How many R squares are needed for platelet count (1 chamber)? {2 chamber)?

A

10 R squares , 20 R squares

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52
Q

What is the area of the central big square in hemacytometer?

A

1sq. mm.

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53
Q

differentiate platelet results of brecker and cronkite from rees-ecker

A

brecker and cronkite - round to oval tiny glistening objects with irregular borders
rees- ecker - lilac colored tiny glistening objects

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54
Q

What is the area of 1 R square in hemacytometer??

A

1/25 sq. mm

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55
Q

what is the hemacytometer used?

A

spencer bright line double counting chamber with improved Neubauer ruling

56
Q

progenitor of brecker and cronkite

A

rees-ecker method

57
Q

[brecker and cronkite]
How many squares should form an X of R squares?

A

9

58
Q

[T or F] For rees- ecker, blood is sucked to 1.0 ml and diluent is sucked to 101 mark

A

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
Q

[brecker and cronkite] how many total r squares are counted for plt count

A

20 r squares (10 squares each chamber)

60
Q

[rees-ecker] how many total r squares are counted for plt count

A

50 r squares (25 each chamber)

61
Q

What to do if the number of platelets in 20 R squares is less than 100?

A

Add more squares until 100 platelets are recorded

62
Q

What to do if the number of platelets in 50 R squares is less than 50?

A

redo test with 1:20 or 1:10 dilution using WBC pipette

63
Q

What are the thrombocytes or platelets?

A

fragments f the outer edges of the megakaryocyte

64
Q

What are not cells, but fragments of the cytoplasm of the mature megakaryocyte or metamegakaryocyte?

A

thrombocytes or platelets

65
Q

What are very small compared to the red blood cells?

A

platelets

66
Q

The platelets are very small compared to what type of cells?

A

red blood cells

67
Q

Where do platelets or thrombocytes accumulate?

A

bone marrow

68
Q

The platelets or thrombocytes are then swept into what?

A

bloodstream

69
Q

[Morphology] Shade of smear is made from? Samples used to make smear.

A

Anticoagulated Blood and Capillary Blood

70
Q

describe newly formed platelets in regards to: size, activity and homeostatic function

A

NEW: large, high activity and effective homeostatic function

71
Q

What cell fragments are derived from?

A

cytoplasm of megakaryocyte

72
Q

[morphology]
Describe platelets in capillary blood

A
  • 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
Q

[morphology]
Describe platelets in anticoagulated blood

A

round, oval to rod-shape ; small

74
Q

Fibrinogen is also needed for what?

A

platelet aggregation

75
Q

What is needed for platelet aggregation?

A

ADP (adenosine diphosphate), Thromboxane (a2) plus fibrinogen

76
Q

What type of aggregation is Fibrinogen needed for?

A

platelet aggregation

77
Q

what biochemicals (with their purpose) are released for primary hemostasis?

A
  1. serotonin - vasoconstrictor
  2. ADP - plt aggregator
  3. thromboxane - vasoconstrictor + plt aggregator
78
Q

what factor is also needed for platelets to attach to the injured blood vessel?

A

von willebrand factor (Factor xvi)

79
Q

What is the process by which serum is expressed from the clot?

A

Clot Retraction

80
Q

What is a contractile protein in the platelets that help in clot retraction?

A

Thrombosthenin

81
Q

What is thrombosthenin

A

contractile protein in platelets that help in expression of serum in clot

82
Q

What is the name for the increase in platelets above normal?

A

Thrombocytosis

83
Q

What is a decrease in number of platelets below normal?

A

Thrombocytopenia

84
Q

platelet distribution in platelet count. explain

A

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
Q

Physiological conditions/ normal variations for platelet count

A
  1. spleen
  2. neonates
  3. menstruating women
  4. arterial blood
  5. venous blood
  6. lymph and other body fluids
86
Q

spleen is also called as the

A

platelet reservoir in man holding 1/3 of the total platelet mass

87
Q

Release of spleenic pool can be triggered by

A
  1. administration of epinephrine
  2. variety of stresses
88
Q

administration of epinephrine / adrenaline can be caused by

A
  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
Q

variety of stressors that can lead to release of spleenic pool

A

HES- HC

  1. hypoxia
  2. excitement
  3. strenuous exercise
  4. high altitude
  5. cold temperatures
90
Q

What is caused by the consumption of platelets?

A

bleeding

91
Q

What does hypoxia cause from the spleen?

A

release of platelets

92
Q

What causes release of platelets from the spleen (spleenic pool)?

A

hypoxia, excitement, strenuous exercise, high altitude, cold temperatures

93
Q

What do those who want to do exercises in the gym have?

A

higher platelet count

94
Q

[T or F] Adults have higher platelets than neonates

A

T

95
Q

[T or F] Neonates have thrombocytopenia at birth

A

T

96
Q

How many days does neonate’s thrombocytopenia last?

A

first 4 days

97
Q

[T or F] neonates have higher platelet count than adults

A

F. Neonates should have slightly lower plt ct than adults

98
Q

What type of capillary blood puncture site has hair which favors adhesion of platelets?

A

earlobe

99
Q

Give disadvantages of dameshek method

A
  1. does not lyse rbcs and wbcs
  2. stable only for 30 mins
100
Q

What is the composition of Rees-Ecker diluent?

A

3.8 g sodium citrate
0.2 ml of 40% formaldehyde
0.1 g of brilliant cresyl blue
100 ml aqueous fluid

101
Q

what are the indirect methods for platelet count?

A

Dameshek method
fonio method
olef method

102
Q

What is the purpose of Na Citrate?

A

anticoagulant

103
Q

what is the diluting fluid used in the dameshek method?

A

rees-ecker diluting fluid

104
Q

platelet count methods

A

indirect and direct methods

105
Q

How many drops of blood do 2 Wipe off?

A

1st

106
Q

How do you let blood flow into the diluent?

A

Gently press the finger

107
Q

How many minutes will allow the settling of the cells to last?

A

15 minutes

108
Q

stability of result in dameshek method

A

30 mins

109
Q

How many RBCs are recorded?

A

1,000

110
Q

Result of platelets in Damesheck method?

A

lilac colored tiny glistening

111
Q

How many fields did one book recommend to count platelets and RBCs?

A

four

112
Q

what does it mean when clumps of platelets are found in your slide during examination/investigation?

A

inadequate mixing

113
Q

What part of the smear does the counting of RBCs take in Fonio method?

A

1/5 ? 1/3 part from end of smear

114
Q

fonio method is also called

A

dry method for indirect platelet counting

115
Q

[fonio method] diluting fluid used

A

14% magnesium sulfate

116
Q

What portion of the smear is well-distributed?

A

thin end portion

117
Q

[fonio method] blood to diluent ratio

A

1:03

118
Q

[T or F] In dameshek method, resulting fluid (Diluent + blood) is thicker than fonio.

A

False. Fonio is thicker than dameshek

119
Q

Where are cells in the thin end portion of the smear?

A

well-distributed

120
Q

What is a dry method?

A

Fonio method

121
Q

Advantages of Fonio method (dry method)

A
  1. easier to count platelets and RBC cuz it is fixed (Dried) and stained
  2. size and shape is observed
122
Q

What is the same principle as Dameshek and Fonio?

A

olef’s method, but this method is more cumbersome

123
Q

What stained blood smear is needed to counter check any procedure in the lab?

A

Wright?s stain

124
Q

What does a platelet/OIF provide?

A

an estimation of platelet numbers, size, and distribution

125
Q

[rees-ecker] ratio of blood to diluent

A

0.180555556

126
Q

[brecker and cronkite] ratio of blood to diluent

A

0.111111111

127
Q

[counter-shecking plt count results
a. <= 1/ OIF
b. 5-20/OIF
c. >25/OIF
d. 1 plt/ 10-30 RBC

A

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
Q

what are the direct methods for platelet count?

A

method of brecker and cronkite (reference method), rees-ecker method, guy and leakes method

129
Q

disadvantage of brecker and cronkite method

A
  1. can lyse rbc but not wbc
  2. stable for reading for 8 hours
130
Q

how many pipettes are used for the modified method of rees-ecker?

A

1 pipetter for both chamber

131
Q

What is the reference method?

A

BRECKER and CRONKITE METHOD

132
Q

What type of methods are available for platelet count?

A

direct, indirect and electronic methods

133
Q

how many pipettes are used for the reference method?

A

2 pipette, 1 per chamber

134
Q

[brecker and cronkite] diluent used

A

1% ammonium oxalate

135
Q

how is indirect and direct method for counting platelets different?

A

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
Q

Microscope used in rees-ecker method and method by brecker and cronkite

A
  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
Q

coverslip required for the reference method

A

no. 1 or 1 1/2 thick coverslip

Hema (3 decks)

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