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37 Cards in this Set

  • Front
  • Back
What does PT stand for?
Prothrombin Time
Which coagulation pathway does PT test measure?
extrinsic and common
What is the main reagent used in PT?
What is the source of thromboplastin in PT?
rabbit brain
How are PT results reported?
What is the normal reference range for PT?
9.0 - 12.0 s
What is the temperature of the PT reagent well?
15 degrees
Why is it important to keep PT reagent at 15 degrees?
the reagent stays stable at this temperature
specimen stability at RT and 4 degrees
< 24 hours
What anticoagulant and ratio is used for coagulation tests?
sodium citrate, 9 blood : 1 citrate
What does ACL stand for?
Automated Coagulation Laboratory
INR: where does 'mean of normal range' come from?
from lab's patient population; labs do a statistical analysis to find the mean
INR: what does isi mean?
International Sensitivity Index
INR: where does INR's gold standard come from?
thromboplastin used by the WHO
What does the isi tell us about the sensitivity of the reagent?
the closer the isi value is to 1.0, the more sensitive it is
where does isi value for the PT reagent come from?
the manufacturer
which coagulation factors are monitored by the PT?
I, II, V, VI, X
how is fibrinogen reported?
what is the normal reference range for fibrinogen?
2.0 - 4.0 g/L
what pathways does the APTT monitor?
intrinsic and common
what are the 2 main ingredients of the APTT reagent?
colloidal silica and phospholipid
what temperature is the APTT reagent kept on the ACL?
15 degrees
what temperature is the APTT analysis carried out?
37 degrees
what temperature is the CaCl2 kept on the ACL?
What is the molarity of the CaCl2 used?
0.025 M
What is the reference range for the APTT test?
28.0 - 34.0 s
which factors are monitored by the APTT test?
XII, XI, IX, VIII (intrinsic)
X, V, II, I (common)
5 reasons for a prolonged APTT
1. liver disease
2. dysfunctional factor(s)
3. DIC
4. Circulating inhibitors
5. short draw
Coagulation factors and Roman numerals that can give a prolonged PT
VII: Stable factor
X: Stuart-Prower factor
V: Labile factor
II: prothrombin
I: fibrinogen
7 coagulation related reactions in which thrombin plays a role
I -> fibrin
V -> Va
XI -> XIa
plasminogen -> plasmin
What PT result can you expect from a patient with PV?
increased because plasma volume is decreased, leaving excess citrate, which binds with calcium in the APTT reagent, causing falsely prolonged clotting times
List Roman numerals and names of coagulation factors that can give elevated APTT results
I Fibrinogen
II Prothrombin
V Proaccelerin
VII Antihemophilic factor
IX Plasma Thromboplastin Component
X Stuart factor
XI Plasma thromboplastin antecedent
XII Hageman factor
follow up tests to investigate elevated APTT results
- factor studies
- mixing studies
- PT test
List Roman numerals and names of coagulation factors that can give elevated PT results
I fibrinogen
II prothrombin
V proaccelerin
X stuart factor
VII proconvertin / stable factor
three conditions that can give prolonged PT results
heparin therapy
oral anticoagulants e.g. warfarin
INR low dose therapeutic range
under what clinical condition is it used?
2.00 - 3.00
with patients on oral anticoagulants
INR high dose therapeutic range
under what clinical condition is it used?
2.50 - 3.50
with patients who have heart valves