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Mercy CLS 7/8: Coagulation/Body Fluids > Coag lab exam > Flashcards

Coag lab exam Flashcards

1
Q

2 platelet count methods

A
  • manual (phase)
  • automated analyzer
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2
Q

platelet count sample

A

EDTA WB

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3
Q

platelets are manually counted with the scope in ——– and on —x

A

phase
40

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4
Q

diluent for plt count and function

A

1% ammonium oxalate
- preserves plts, WBCs, nRBCs
- lyses RBCs

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5
Q

plt count dilution

A

1:100

1.98 mL ammonium oxalate + 20 μl blood

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6
Q

a plt count dilution is good for —– hours

A

3

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7
Q

plt clumping or satellitism
cause
solution

A

EDTA sensitivity
recollect in Na citrate

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8
Q

3 methods of automated plt ct

A
  • impedance (PLT-I)
  • optical (PLT-O)
  • fluorescent (PLT-F)
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9
Q
A
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10
Q

electric current is blocked as plts pass through

based on size only

A

impedance method

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11
Q

impedance method of plt count interferences

A
  • giant plts
  • schistocytes
  • small microcytes
  • plt clumps
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12
Q

uses light scattering properties to distinguish plts based on internal complexity

A

optical method

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13
Q

uses fluorescent dye to stain plt organelles

A

fluorescent method

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14
Q

RR and critical range for plt count

A

150-400 x 10^3/μL
<20 x 10^3/μL

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15
Q

performed when plts are “flagged” on analyzer to verify accuracy of instrument’s count

A

platelet estimate

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16
Q

uses a 20 μL capillary tube for dilution

A

manual platelet count

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17
Q

let plt dilution sit for —– mins to allow RBCs to lyse

A

5

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18
Q

which squares are plts counted in?

A

5 smaller squares (area of 0.2 mm^2)

if plt count <40 in these squares, count entire large center square

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19
Q

plt count calculation

A

plts/μL = (plts counted)(100)(10)/0.2

100 = DF
0.2 = area

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20
Q

plt estimate procedure

A
  • scan entire feathered edge on 10x for clumps/fibrin strands
  • in monolayer, count platelets in 5 fields and find average
  • multiply average by 15 and 20 to get a range
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21
Q

tests associated with primary hemostasis

A
  • plt count
  • bleeding time
  • plt function assay
  • plt aggregation studies
  • flow cytometry
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22
Q

tests associated with secondary hemostasis

A
  • PT
  • PTT
  • TT
  • Fibrinogen
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23
Q

tests associated with fibrinolytic system

A
  • FDPs
  • D-dimers
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24
Q

things to avoid during venipuncture

A
  • TF entering sample
  • do not draw tube with anticoag or clot promoter before the Na citrate
  • hemolysis
  • heparin contamination
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25
Q

how to avoid heparin contamination

A
  • flush line with saline
  • discard 1st 5 mL blood
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26
Q

coag tubes are —– Na citrate with —— anticoagulant:blood ratio

A

3.2%
1:9

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27
Q

function of Na citrate

A

chelates Ca++ in blood

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28
Q

if there is a sample volume <85% with Na citrate…

A

test results must be prolonged because excess additive will chelate Ca++ in the reagents

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29
Q

Hct —— may prolong test results because less plasma requires less Na citrate

A

> 55

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30
Q

what makes Na citrate a good additive?

A
  • good preservative for factor V
  • sensitive to heparin, so pts can be monitored
  • better for ABS reading instruments because it doesn’t create precipitate
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31
Q

——– plasma is used for most coag tests

procedure

A

platelet poor

spin to reach plt <10,000/μL

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32
Q

handling and longevity of plt poor plasma

A
  • good 4 hours RT or refrigerated
  • 2 hours if pt on heparin
  • keep capped until analyzed
  • no repeated freezing/thawing
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33
Q

——— plasma is used for plt aggregation studies

procedure

A

platelet rich

spin at lower speed to obtain plt count of 200-300 x 10^3

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34
Q

handling and longevity of plt rich plasma

A
  • good for 3 hours RT
  • do not freeze
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35
Q

why can’t glass be used for coag samples?

A

negative charge causes contact activation of intrinsic pathway

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36
Q

old screen for platelet function
measures primary plt plug

A

bleeding time

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37
Q

factors that affect bleeding time

A
  • plt function
  • plt count (<100 will prolong, do count first)
  • vessel integrity
  • aspirin, clopidogrel (avoid 7 days prior)
  • technique
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38
Q

automated screening method for plt function, which replaced bleeding time

A

platelet function assay

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39
Q

PFA uses a cartridge containing…

A

a collagen membrane coated with platelet agonist, such as epinephrine or ADP

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40
Q

collagen/epinephrine membrane used in PFA for…

A

plt dysfunction due to plt defects or inhibitors

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41
Q

collagen/ADP membrane used in PFA to…

A

determine if abnormal epinephrine result is due to aspirin

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42
Q

aspirin effect on PFA

A

epinephrine abnormal, ADP normal

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43
Q

what affects bleeding time but not PFA?

A

vessel integrity

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44
Q

sample handling for PFA

A
  • do not spin
  • cannot go through pneumatic tubes
  • must stay at RT
  • run within 3 hours
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45
Q

aggregating agents added
light transmission increases

A

aggregation studies

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46
Q

used to measure light transmittance for plt aggregation

A

aggregometer

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47
Q

aggregating agents

A
  • collagen
  • ADP
  • epinephrine
  • ristocetin
  • arachidonic acid
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48
Q

no ——– 7 days prior to plt aggregation study

A

aspirin

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49
Q

monophasic pattern of plt aggregation

A

collagen
ristocetin
arachidonic acid

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50
Q

biphasic pattern of plt aggregation

A

ADP
epinephrine

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51
Q

biphasic pattern of plt aggregation occurs when…

A

ADP released from dense bodies of plts

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52
Q

ristocetin represents ———– of plts and depends on interaction of —- and —–

A

agglutination
vWF and GPIb

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53
Q

how to tell difference between ristocetin aggregation from VWD and from Bernard-Soulier syndrome

A

VWD: corrects with normal plasma added
BSS: does not correct with normal plasma added

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54
Q

flow can be used to dx…

A

Bernard-Soulier syndrome
Glanzmann thrombasthenia

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55
Q

most reagents for 2°hemostasis tests are ———– and must be reconstituted with ———-

A

lyophilized
purified water (NERL)

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56
Q

when does QC for the 2° hemostasis tests need to be done?

A
  • every 8 hours
  • new reagent bottle
  • after maintenance
  • after problem with instruments or reagnets
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57
Q

fibrin endpoint systems detect…

A

unstable fibrin clot, factor XIII not yet activated (so XIII problems not detected)

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58
Q

2 automated methods for 2° hemostasis tests

A
  • optical (ABS reading)
  • mechanical (use a magnetic bead)
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59
Q

STAGO

A

evolution and compact instruments
use magnetic bead for 2° hemostasis tests

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60
Q

mechanical 2° hemostasis methods are not sensitive to…

A

hemolysis, icerus, lipemia

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61
Q

POC test used to estimate effectiveness of protamine sulfate dose (used to absorb heparin after cardiac surgery)

A

whole blood clotting time

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62
Q

—- used to monitor coumadin tx
—- used to monitor heparin tx

A

PT
PTT

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63
Q

not sensitive to slightly ↓ fibrinogen (must be <100 mg/dL)

A

PT

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64
Q

uses TF preparation to activate cascade by forming TF/VII complex and detecting clot

A

PT

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65
Q

PT RR

A

12-15 sec

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66
Q

how does each lab establish its PT RR?

A

run at least 30 normal plasma samples, half male and half female

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67
Q

——— will not interfere with PT unless ↑↑

A

heparin

absorbent in reagent

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68
Q

coumadin action

A

inhibit production of vitamin K dependent factors in liver

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69
Q

used to standardize PT results for coumadin monitoring

A

international normalized ratio

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70
Q

ISI

A

international sensitivity index

supplied by manufacturer of each lot of thromboplastin for PT

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71
Q

INR =

A

INR = R^ISI

R = PR ratio = pt PT/mean normal PT
ISI supplied with reagent

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72
Q

INR TR

A

2.0-3.0

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73
Q

factors that affect efficacy of oral anticoag

A
  • dosage
  • vitamin K in diet
  • body mass
  • drugs (antibiotics, aspirin)
  • liver function
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74
Q

why do antibiotics affect coumadin dosing?

A

↓ normal flora
↓ vitamin K made by them
↓ dose

75
Q

↑ INR at risk for…

A

bleeding

76
Q

3 uses for PTT

A
  • detect deficiencies in intrinsic/common pathway
  • monitoring heparin therapy
  • detecting inhibitors
77
Q

activated partial thromboplastin provides PL surface and activator with negative surface

CaCl2 provides Ca++

A

PTT

78
Q

activators present in PTT reagent

A

kaolin
silica

79
Q

PTT RR

A

25-35 sec

80
Q

coag factors must be ——% of normal or less to cause abnormal PTT

A

25-40

81
Q

is sensitive to slightly ↓ fibrinogen

A

PTT

82
Q

better than PTT for monitoring heparin therapy

A

anti-Xa test

83
Q

function of heparin

A

enhances action of ATIII on thrombin and Xa

neutralizes IXa and XIa

84
Q

run PTT —- hours after changing heparin dose

A

6

85
Q

there is no standard, such as INR, available for…

A

PTT monitoring of heparin

86
Q

how is heparin therapeutic range determined?

A

correlating PTT results from patients on heparin with Xa inhibition results

87
Q

neutralize heparin

A
  • PF4 (trauma, cold storage)
  • protamine sulfate
88
Q

Xa inhibition assay should be used…

A
  • acute phase reactants present (early in DVT, PE)
  • LMW heparin used
89
Q

action of acute phase reactants on heparin

A

compete with ATIII for heparin binding sites, making PTT unreliable

used anti-Xa assay

90
Q

prophylactic heparin given IM
usually doesn’t need monitoring

A

LMW heparin

91
Q

advantage of LMW heparin over unfractionated heparin

A

unfractionated heparin patients tend to make platelet Ab

LMW heparin does not cause this

92
Q

anti-Xa is a ———– assay using a standard curve

A

chromogenic

93
Q

factor Xa inhibition assay TR

A

0.3-0.7 U/mL

94
Q

deheparinzed plasma reagent can absorb up to —— heparin

A

10 mL

95
Q

use of deheparinized plasma

A
  • remove heparin contamination
  • for coumadin effect when pt is being converted from heparin to coumadin (if PT reagent sensitive to heparin)
96
Q

mesaures conversion of fibrinogen to fibrin

A

TT

97
Q

function of TT

A

look for circulating thrombin inhibitors

98
Q

rate limiting factor in TT is…

A

thrombin in pt plasma

99
Q

TT RR

A

15-19 sec

100
Q

5 causes of abnormal TT

A
  • FDPs
  • ↓ fibrinogen
  • dysfibrinogenemia
  • thrombin inhibitor
  • heparin
101
Q

major difference between TT and Fib

A

TT: low level thrombin + undilute plasma
Fib: excess thrombin + dilute plasma

102
Q

used to quantitate fibrinogen

A

Fib

103
Q

Clauss assay reference method

A

Fib

104
Q

TT performed on 1:10 dilution of plasma and control

A

Clauss method of Fib

105
Q

rate limiting factor in Fib is…

A

pt fibrinogen concentration

106
Q

Fib is ———– to TT

A

inversely proportional

107
Q

Fib RR

A

150-350 md/dL

108
Q

performed if PT and PTT are normal, but pt is bleeding or clotting

A

FDPs/D-Dimer

109
Q

FDP in plasma indicates —– fibrinolytic activity

A

↑

110
Q

FDP method

A

serum latex agglutination

111
Q

conditions that can cause ↑ FDPs

A

DIC
liver/kidney/heart disease
MI
carcinoma
PE
DVT
eclampsia

112
Q

D-dimer has excellent ———- predictive value for DVT

A

negative

113
Q

4 parts of DIC panel

A

PT
PTT
fibrinogen
D-dimer

114
Q

↑ FDPs
normal D-dimer

A

fibrinogenolysis

115
Q

differentiates factor deficiencies from circulating inhibitors

A

mixing studies

116
Q

mixing study corrected =
mixing study not corrected =

A

factor deficiency
inhibitor

117
Q

2 rounds of mixing studies

A

immediately
after 2 hours 37° incubation

118
Q

time/temp dependent inhibitor

A

VIII

119
Q

abnormal mixing study is followed by…

A

factor or inhibitor assay

120
Q

uses single factor deficient substrate to determine if dilutions of pt plasma correct it

A

factor assay

121
Q

factor assay corrected =

A

patient is not deficient

122
Q

used with TT to differentiate FDPs, dysfibrinogenemia, and heparin contamination

A

reptilase time

123
Q

enzyme that cleaves fibrinopeptide A

A

reptilase

124
Q

reptilase time RR

A

18-22 sec

125
Q

———- time not affected by heparin

A

reptilase

126
Q

TT ↑↑
reptilase ↑

A

FDPs

127
Q

TT ↑
reptilase ↑↑

A

dysfibrinogenemia

128
Q

TT ↑↑
reptilase normal

A

heparin contamination

129
Q

uses extended incubation with first reagent in PTT

A

prekallikrein screening test

130
Q

PK screen corrects =

A

prekallikrein deficiency

131
Q

used to detect XIII deficiency

A

urea solubility test

132
Q

fibrin clot is insoluble in 5M urea if…

A

XIII is present

133
Q

5M urea clot dissolves =

A

XIII deficiency

134
Q

plasma clotted with CaCl2
5M urea added
24 hour RT incubation

A

XIII screening test

135
Q

XIII must be ——% to be detected and to be clinically significant

A

<1-2%

136
Q

2 general types of assays for factor deficiencies

A
  • activity assays - determine function
  • immunoassays - determine quantity
137
Q

RCoF assay

A

vWF activity assay

138
Q

measures ability of vWF to agglutinate standard suspension of platelets in presence of ristocetin

A

RCoF assay

139
Q

microtiter ——– used for vWF:Ag immunoassay

A

ELISA

140
Q

↓ vWF:Ag

A

type I and III VWD

141
Q

normal vWF:Ag

A

type II VWD

142
Q

used to confirm type of VWD

A

SDS PAGE multimer analysis

143
Q

all multimers of vWF ↓

A

VWD I

144
Q

only HMW multimers of vWF ↓

A

VWD II

145
Q

all multimers of vWF absent

A

VWD III

146
Q

2 most common factor inhibitors

A
  • lupus-like anticoagulant
  • VIII inhibitor
147
Q

inhibitor causing clotting

A

lupus-like

148
Q

anti-PL inhibitor

A

lupus-like

149
Q

3 steps to ID lupus-like inhibitor

A
  1. clotting assay (prolonged PTT)
  2. mixing studies
  3. reduce or add excess PL to see if it corrects
150
Q

plt neutralization procedure for LLAC

A
  • ruptured platelets neutralize anti-PL
  • if PTT corrects, LLAC is present

false pos with heparin; PF4 neutralizes it

151
Q

LLAC methods that use ↑ PL and ↓ PL

A

↑ PL: platelet neutralization; STAclot LA
↓ PL: dRVVT

152
Q

dRVVT

A

dilute russel viper venom test

LLAC activity ↑ as PL content ↓

153
Q

dRVV activates —– in plasma

A

X

154
Q

abnormal dRVVT ratio =

A

LLAC present

155
Q

uses PTT reagent with increased PL content

A

STAclot LA

156
Q

EIA test to pick up configurations of anti-PL that other tests don’t detect

A

anti-cardiolipin Ab test

157
Q

LLAC can bind PL on ——–, blocking ——–

A

VECs
protein C

158
Q

uses dilute pt plasma with normal pooled plasma that has a known VIII activity

A

factor VIII inhibitor assay

159
Q

thrombophilia

A

hypercoagulable state
repeated thrombotic episodes

160
Q

ATIII assays use ——- as a target

A

thrombin or Xa

161
Q

during ATIII chromogenic assay, thrombin releases ————- from substrate

A

p-nitroaniline

162
Q

more ATII = —— color

A

↓

163
Q

inherited deficiencies of ATIII

A
  • ↓ ATIII
  • dysfunctional ATIII
164
Q

acquired deficiencies of ATIII

A
  • DIC
  • liver disease
  • nephrotic syndrome
  • OC/estrogen
  • malignancy
165
Q

protein C is quantitated by —– assay

A

EIA

166
Q

protein C assay uses ——– to activate PC

A

thrombin or thrombomodulin complex

167
Q

protein C assay is based on ability of PC to ———— PTT by…

A

prolong
inactivating Va and VIIIa

168
Q

acquired protein C deficiencies

A
  • DIC
  • vit K deficiency
  • liver disease
  • oral anticoag
  • postsurgical
169
Q

2 forms of protein S

A
  • free (40%), serves as cofactor
  • bound to C4b (60%)
170
Q

acquired protein S deficiencies

A
  • liver disease
  • pregnancy
  • OC
  • DIC
  • T1DM
  • oral anticoag
171
Q

deficiency of —— or excess of ——- seen in in inflammatory states, associated with hypercoagulation

A

t-PA
PAI-1

172
Q

useful in monitoring fibrinolytic tx (used to dissolve existing clots)

A

antiplasmin assay

173
Q

used to detect factor V leiden mutation

A

activated protein C resistance test

174
Q

factor V leiden mutation causes…

A

V to be resistant to degradation by protein C

175
Q

—- should be initially normal or FVL mutation test is invalid

A

PTT

176
Q

used to confirm FVL mutation dx

A

PCR

177
Q

effect of prothrombin mutation

A

↑ prothrombin levels up to 30% higher than normal

risk for thrombosis

178
Q

deficiency of enzyme needed to convert homocysteine to methionine

A

methylene tetrahydrofolate reductase mutation

179
Q

useful for TTP dx

A

ADAMTS-13 mutation or auto-Ab

180
Q

vWF-cleaving protease

A

ADAMTS-13

181
Q

unusually large vWF multimers

A

TTP

182
Q

associated with ADAMTS-13 mutation

associated with auto-Ab against enzyme

A

chronic relapsing TTP

acute TTP

183
Q

—— assay used for ADAMTS-13 antigen or Ab

A

ELISA

Mercy CLS 7/8: Coagulation/Body Fluids (9 decks)

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