Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Coagulation, Urinalysis & body fluids > Lab testing in Coagulation > Flashcards

Lab testing in Coagulation Flashcards

1
Q

Coagulation testing temperature

A

always at 37 C

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Coag specimen

A

plasma w/ sodium citrate (3.2%) at 9:1 ratio

requires Ca2+ to be added to the testing bc sodium citrate will bind all available calcium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Platelet-Poor plasma (PPP)

A

plasma containing less than 10x10^9/L platelets

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Platelet-Rich Plasma (PRP)

A

plasma containing ~200-300x10^9/L

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Testing of Primary Hemostasis

A

peripheral smear, platelet count, platelet aggregation, bleeding time & platelet function analyzer, platelet secretion studies, flow cytometry

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Specimen problems w/ platelet counts & estimates

A

clumping- due to capillary puncture
satellitism - caused by EDTA & leads to falsely low counts
giant platelets- counted as WBC; falsely low count
fragmented RBCs- ocunt as plt; falsely elevated count

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Platelet aggregation studies

A

addition of aggregating reagent to PRP - measure change in transmittance
2 waves: primary & secondary
* know charts on slide 21 in lab testing pdf

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Bleeding time

A

measure of platelet function
3 types: duke, ivy, template (!)
prolonged w/ aspirin etc

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Bleeding time: template

A

standardized back pressure & standardized depth
normal bleeding time 1-9 minutes
not very sensitive
should NOT be performed if plt count is less than 100x10^9/L

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Platelet function analyzer

A

replaces the BT- eliminates many of the variables
pumps whole blood (in citrate) through each of 2 apertures containing either : collagen/epi or collagen/ADP
& measures time necessary for plt to occlude the aperture

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Flow cytometry for primary hemostasis

A

useful for GPlb/IX deficiency (Bernard-Soulier) & GPIIB/IIIa deficiency (Glanzmann’s thrombasthenia)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Testing of Extrinsic pathway

A

prothrombin time (PT)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Prothrombin time (PT)

A

screen for inherited or acquired deficiencies in the extrinsic & common pathway
measures factors: I, II, V, VII & X
monitors oral anticoagulant therapy- coumadin /warfarin
range 10-13 seconds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

PT procedure

A

specimen & reagents & 37C

plasma specimen + thromboplastin reagent (contains Ca2+)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

PT & INR

A

INR is the international normalized ratio

used to correct for differences in coag instruments

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

INR formula

A

INR = (PT patient/ PT normal) ^ISI
0 to >6
theraputic is 2-3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

PT sources of error

A

short draw - falsely shorten the PT
delay between collection & teting may lead to decreases in factor V
patient high hematocrit- can lead to prolonged PT

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Testing of Intrinsic pathway

A

APTT or PTT-performed by adding platelet phospholipid substitute & contact activator (APTT reagent) & Ca2+ to activate factor XII

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

APTT

A

screen for intrinsic & common pathway
measures all factors except VII (extrinsic) & XIII
28-35 seconds
monitors heparin therapy

20
Q

sources of error for APTT

A

blood collection error (short draw)
hematocrit
sample processing etc

21
Q

Activated Clotting time (ACT)

A

used to monitor the effectiveness of high dose heparin therapy
not performed in the clinical lab - point of care test

22
Q

Thrombin Clotting time

A

thrombin time TT, TCT
measures clotting time of the last step in the coag cascade- fibrinogen (!) to fibrin by thrombin (test of common pathway)
used to detect dysfibrinogenemia

23
Q

TCT source of error

A

collection etc

can be falsely prolonged due to heparin

24
Q

Reptilase Time

A

clotting time similar to thrombin time except that a snake venom is used instead of thrombin
reptilase is a thrombin like enzyme
NOT PROLONGED BY HEPARIN

25
Q

Fibrinogen Assay

A

recommended test for estimating fibrinogen level
high [thrombin] is inversely proportional to [fibrinogen]
thrombin reagent is 25x more concentrated than in TCT, patient plasma needs to be diluted

26
Q

APTT normal &

PT abnormal

A

possible causes:

  1. factor deficiency in extrinsic pathway probably VIII
  2. specific factor inhibitor
27
Q

APTT abnormal &

PT normal

A

possible causes:

  1. Factor deficiency in intrinsic pathway (XII, XI, kallikrein, IX, or VIII)
  2. Specific factor inhibitor
  3. lupus anticoagulant
28
Q

APTT abnormal
PT abnormal
TCT normal

A

possible causes:

  1. factor deficiency in common pathway
  2. vitamin K defect
  3. liver disease
  4. inhibitor present
29
Q

APTT abnormal
PT abnormal
TCT abnormal

A

possible causes:

  1. factor deficiency (I)
  2. severe liver disease
  3. DIC
  4. inhibitor
30
Q

Test to evaluate specific factor deficiency

A

when PT &/or APTT are prolonged

  1. mixing studies-differentiate factor def. from inhibitor
  2. specific factor assay
31
Q

Mixing study

A

performed to differentiate between factor deficiency & inhibitor
this procedure will correct the prolonged PT or APTT if it is caused by a deficiency of one or more of the coag factors

32
Q

Mixing study precedure

A

patient’s plasma mixed 1:1 w/ normal plasma
if normal then factor deficiency is suspected
if NOT normal then suspect an inhibitor
rerun after heating for 2 hours
if APTT is still normal = factor def.
then perform specific factor assay!

33
Q

Mixing study results for Factor deficiency

A

immediate mixing study: corrected

after 2 hour incubation: corrected

34
Q

Mixing study results for Lupus-like anticoagulant

A

immediate mixing study: no correction

after 2 hour incubation: no correction

35
Q

Mixing study results for Specific inhibitor (factor VIII)

A

immediate mixing study: correction

after 2 hour incubation: no correction

36
Q

Factor Assay

A

performed to confirm a specific factor deficiency & to determine the actual activity of that factor w/in the plasma
the degree of correction produced w/ the patient’s plasma is compared to a reference curve
most likely will be Factor VIII

37
Q

Fibrinolytic System

A

2 major tests:

Fibrin degradation products & D-dimer

38
Q

Fibrin Degradation Products (FDPs)

A

Plasmin cleaves fibrin & yields FDPs
normally D & E fragments do not reach plasma concentrations of 2 um/mL
assay test based on antigen-antibody reaction

39
Q

Increased FDP is seen in:

A

DIC, deep vein thrombosis, pulmonary embolism, liver disease, alcoholic cirrhosis, kidney disease, etc etc etc

40
Q

D-dimer Assay

A 
more specific test for plasmin lysis of fibrin beginning to replace FDPs
excellent marker for DIC (positive)
3 methodologies: 
semiquantitative assay 
quantitative assay
latex agglutination
41
Q

Testing of Thrombophilia

A

antithrombin assays
protein C assays
protein S assays

42
Q

Mechanical clot detection

A

incorporates a change in electrical conductivity between 2 metal electrodes immersed in a solution
when clot formed, fibrin strands act as conductor between probes causing constant electrical current

43
Q

Photo-optical detection of clot formation

A

measured by a change in optical density of a test sample

widely used today

44
Q

Chromogenic detection of clot formation

A

color intensity is measured spectrophotometrically & is directly proportional to the concentration of chromophore tag

45
Q

Immunologic detection methods of clot formation

A

antigen level is proportional to the amount of light absorbed

Coagulation, Urinalysis & body fluids (4 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions