International Normalize Ratio Flashcards
This is a standardized way of reporting PT in monitoring
oral anticoagulant therapy, calculated as a ratio of the
patientβs PT to a control PT standardized for the potency
of the thromboplastin reagent developed by the World
Health Organization
International Normalized Ratio
Formula of INR?
πΌππ = {(πππ‘ππππ‘ ππ) / ππ (ππππ‘πππ ππππ} πΌπI
International Sensitivity Index stands for?
ISI
(calibration index) and indicated on the reagent bottle?
ISI
high risk for bleeding; blood is thin means Greater or Lesser INR?
Greater than INR
Reference values for INR for 2.0-3.0?
β In prevention and treatment of venous
thrombosis
β Treatment of pulmonary embolism
β Prevention of stroke in myocardial infarction
β Peripheral arterial disease
β Prevention of systemic embolism in atrial
fibrillation
β Cardiac valve replacement (tissue valve)
High risk for thrombosis; blood is viscous means Greater or Lesser INR?
Less than INR
This uses a venom from Vipera russelli or Daboia
russelli, which has a thromboplastin-like action?
Stypven time or Russell viper venom test
Reference values for INR for 2.5-3.5?
β In prevention of recurrent MI
β Reduction of mortality in MI
β Mechanical prosthetic heart valve (high risk)
Stypven time or Russell viper venom test uses what venum?
Vipera russelli or Daboia
russelli
Stypven time is similar to Factor?
VIIa-TF complex
Addition of the venom bypasses the activation of
VII and directly activates factor X
Vipera russelli or Daboia
russelli
Dilute Russell viper venom time, together with APTT, is
used to test for (?) which inhibits
phospholipid
lupus anticoagulant
INDIRECT TESTS
Thrombin time
Reptilase time
Dukert test
- This is a modification of thrombin clotting time by
Clauss - This measures the availability of functional fibrinogen;
used to monitor heparin therapy and is sensitive to the
presence of increased levels of FSP
Thrombin time (fibrinogen deficiency test)
Other name of Thrombin time?
(fibrinogen deficiency test)
Thrombin time Specimen? and diluted to?
citrated PPP (diluted at 1:10)
Thrombin time Reagent?
standardized thrombin solution and calcium
Thrombin time Reference time
17-25 seconds
Causes of prolonged thrombin time
Fibrinogen level is below 75-100 mg/dL
β Functional disorder of fibrinogen
β Presence of heparin, FSP, and thrombolytic agents
β Normally prolonged in newborns and in multiple
myeloma
This uses the reagent reptilase enzyme, collected from
Bothrops atrox, which has a thrombin-like effect
Reptilase time
Reptilase time uses the reagent (?), collected from (?), which has a thrombin-like effect
reptilase enzyme, Bothrops atrox
This anticoagulant is unable to inhibit reptilase
Heparin
Reptilase time Reference time
18-20 seconds
Dukert test is also called?
t (5M urea solubility test)
Causes of prolonged reptilase time:
Fibrinogen deficiency and other functional
disorders of fibrinogen
β Presence of FSP
- PT is performed on serum
- Deficiency in factors V, VIII, IX X, XI, XII, or platelets will
slow the rate of (?) leaving
significant amount of prothrombin in the serum
Prothrombin consumption time
In duker test, If (?) is deficient in the patientβs plasma,
the clot is dissolved in less than (?) by the
urea
factor XIII, 24 hours
Clot formed in normal plasma is insoluble in 5M
urea during a 24-hour incubation
Dukert test (5M urea solubility test)
- If the residual prothrombin is (?), there is deficiency
in coagulation factors
> 20%
Deficiency in factors in Prothrombin consumption time?
factors V, VIII, IX X, XI, XII, or platelets
Thromboplastin generation time made by?
Biggs and
Douglas
This uses BaSO4/Al(OH)3-adsorbed plasma or fresh
serum
Thromboplastin generation time
This is a modification of thromboplastin generation
time and requires recalcification of diluted plasma
Hicks-Pitney test
: a semi-automated mechanical instrument
that detects fibrin strand formation using a wire loop or
hook and it is under what type of automation?
Fibrometer, Electromechanical
Fibrometer checks for fibrin threads every (?)
which allows more accuracy
0.5 seconds
This depends on the increase in light scattering
associated with the conversion of soluble fibrinogen
molecules to the insoluble polymerized fibrin clot
Photo-optical
What are the Semi-automated instruments?
Electra 750 and 750A;
Fibrintimer series; and FP 910 Coagulation Analyzer
what are the Automated instruments?
Ortho Koagulab 16S and 40A;
COag-A-Mate X2 and XC; MLA Electra 700 and 800
This is performed when PTT and PT are prolonged to
determine whether it is caused by a nonspecific
inhibitor, specific inhibitor, or coagulation factor
deficiency, and to determine the deficient coagulation
factor
MIXING OR SUBSTITUTION STUDIES
To determine if it is factor deficiency and or inhibitor, we will add?
Normal fresh plasma
Fiirst to dissappear and shortest life span in vivo
VII
When it become uncorrected, it means?
Presence of pathological circulating anticoagulant
Under Presence of pathological circulating anticoagulant, Specific inhibitor means using?
perform APTT and DRVVP
Adsorbed plasma (present)
I, V, VIII, XI, XII, XIII, HK, PK
Fresh plasma (present)
All factors
what is need to do in Identification of deficient factor
mix equal parts of
patientβs plasma + an appropriate mixing sample
Under Presence of pathological circulating anticoagulant, Non Specific inhibitor means using?
. lupus anticoagulant;
Bethesda assay (screening); immunoassay
(confirmatory)
Aged plasma (present)
I, II, VII, IX, X, XI, XII, XIII,
PK, HK
if repeated test is corrected when
mixed with normal plasma, it means?
Factor deficiency
Fresh plasma (absent)
None
Aged plasma (absent)
V, VIII
Fresh serum (absent)
I, V, VIII, XIII
Fresh serum (present)
II, VII, IX, X, XI, XII, HK,. PK
Adsorbed plasma (absent)
II, VII, IX, X
Aged serum (present)
VII, IX, X, XI, XII, HK, PK
Aged serum (absent)
I, II, V, VIII, XIII
Adsorbed serum (present)
XI, XII, HK, PK
Adsorbed serum (absent)
I, II, V, VII, VIII, IX, X, XII
PT normal and APTT prolonged
Intrinsic: VIII, IX, XI, XII, HMWK, PK
PT Prolonged and APTT prolonged
Common: I, II, V, X
Sample problem:
PT and APTT: prolonged
β Adsorbed plasma
X Fresh serum
Factor I and V is deficient
PT prolong and APTT normal
Extrinsic: VII
Sample problem:
PT and APTT: prolonged
β Aged serum
X Adsorbed plasma
Factor X is deficient
Sample problem:
PT: normal and APTT: prolonged
β Adsorbed plasma
X Fresh serum
Factor VIII is deficient
Sample problem:
PT: normal and APTT: prolonged
β Aged serum
X Adsorbed serum
Factor IX is deficient
(modification of thrombin time by
Clauss
Fibrinogen assay
Used for diagnosis of types of hemophilia
Single factor assay using PTT and PT
common to occur and
produces severe bleeding
Hemophilia A and B
rare to occur and does not produce
severe bleeding
Hemophilia C
is performed on patientβs diluted plasma, with 3-4
dilutions (1: 10; 1:20; 1:40; 1:80)
APTT
The interval of the test is compared to the
laboratoryβs
reference curve (percent activity