View
266
Download
1
Category
Tags:
Preview:
Citation preview
Bleeding time,clotting time, PT, and PTT
Ostadrahimi MD,PhD
Hemostasis or haemostasis : is a complex process which causes
the bleeding process to stop. It refers to the process of keeping blood within a damaged blood vessel.
THE CLOTTING MECHANISM
INTRINSIC EXTRINSC
PROTHROMBIN THROMBIN
FIBRINOGEN
FIBRIN(II) (III)
(I)V
X
Tisue ThromboplastinCollagen
VII
XII
XI
IXVIII
THROMBOCYTOPATHY )ADEQUATE NUMBER BUT ABNORMAL FUNCTION .(
causes UREMIA INHERITED DISORDERS MYELOPROLIFERATIVE DISORDERS
DRUG INDUCED(ASPIRIN, NSAIDS)
FACTOR DEFICIENCIES
Inherited:1. HEMOPHILIA A
2. HEMOPHILIA B
3. VON WILLEBRAND’S DISEASE
Acquired:
1. Anticoagulant therapy
2. Liver diseases
3. DIC
LABORATORY EVALUATION
PLATELET COUNTBLEEDING TIME (BT)PROTHROMBIN TIME (PT)PARTIAL THROMBOPLASTIN TIME (PTT)THROMBIN TIME (TT)
PLATELET COUNT (CBC)
NORMAL 100,000 - 400,000 CELLS/MM3
<100,000 Thrombocytopenia
50,000 - 100,000Mild Thrombocytopenia
<50,000 Sever Thrombocytopenia
BLEEDING TIME
PROVIDES ASSESSMENT OF PLATELET COUNT AND FUNCTION
NORMAL VALUE
2-8 MINUTES
PROTHROMBIN TIME
Measures Effectiveness of the Extrinsic Pathway
NORMAL VALUE
10-15 SECS
PT The prothrombin time: is therefore the time required for the
plasma to clot after an excess of thromboplastin and an optimal concentration of calcium have been added.
Measures the function of the Extrinsic Pathway. Sensitive to Factors I, II, V, VII, X.
The PT evaluates patients suspected of having an inherited or acquired deficiency in these pathways.
THE CLOTTING MECHANISM
INTRINSIC EXTRINSC
PROTHROMBIN THROMBIN
FIBRINOGEN
FIBRIN(II) (III)
(I)V
X
Tisue ThromboplastinCollagen
VII
XII
XI
IXVIII
When is it ordered?
Used to monitor oral anticoagulant therapy (Warfarin / Coumadin).
When a patient who is not taking anti-coagulant drugs has signs or symptoms of a bleeding disorder.
When a patient is to undergo an invasive medical procedure, such as surgery, to ensure normal clotting ability.
An elevated prothrombin time may indicate the presence of:
Vitamin K deficiency(Vitamin K is needed to make prothrombin and other clotting factors)
DIC liver disease a deficiency in one or more of the following factors: I, II, V, VII, X. Anticoagulant (warfarin)
INR
A PT test may also be called an INR test. INR (international normalized ratio) stands for a way of
standardizing the results of prothrombin time tests, no matter the testing method.
So your doctor can understand results in the same way even when they come from different labs and different test methods.
Using the INR system, treatment with (anticoagulant therapy) will be the same. In some labs, only the INR is reported and the PT is not reported
An INR of 1.0 means that the patient PT is normal. An INR greater than 1.0 means the clotting time is
elevated. INR of greater than 5 or 5.5 = unacceptable high risk of
bleeding,whereas if the INR=0.5 then there is a high chance of having a clot.
Normal range for a healthy person is 0.9–1.3, and for people on warfarin therapy, 2.0–3.0, although the target INR may be higher in particular situations, such as for those with a mechanical heart valve.
PARTIAL THROMBOPLASTIN TIME
Measures Effectiveness of the Intrinsic
Pathway
NORMAL VALUE
25-40 SECS
PTT
The partial thromboplastin time (PTT) or activated partial thromboplastin time (aPTT or APTT( is a performance indicator measuring the efficacy of both the "intrinsic" and the common coagulation pathways.
It is also used to monitor the treatment effects with heparin a major anticoagulant.
Kaolin cephalin clotting time (KccT) is a historic name for
the activated partial thromboplastin time
THE CLOTTING MECHANISM
INTRINSIC EXTRINSC
PROTHROMBIN THROMBIN
FIBRINOGEN
FIBRIN(II) (III)
(I)V
X
Tisue ThromboplastinCollagen
VII
XII
XI
IXVIII
Normal PTT times require the presence of the following coagulation factors:
I, II, III, IV, V, VI, VIII, IX, X, XI, & XII
When is it ordered?
When a patient presents with unexplained bleeding or bruising,
It may be ordered as part of a pre-surgical evaluation for
bleeding tendencies,
When a patient is on intravenous (IV) or injection heparin
therapy, the APTT is ordered at regular intervals to monitor the degree of anticoagulation.
Prolonged APTT may indicate:
use of heparin.
antiphospholipid antibody:especially lupus anticoagulant, which paradoxically increases propensity to thrombosis
coagulation factor deficiency ,
e.g hemophilia DIC Liver disease
THE CLOTTING MECHANISM
INTRINSIC EXTRINSC
PROTHROMBIN THROMBIN
FIBRINOGEN
FIBRIN(II) (III)
(I)V
X
Tisue ThromboplastinCollagen
VII
XII
XI
IXVIII
FACTOR DEFICIENCIES
Inherited:1. HEMOPHILIA A
2. HEMOPHILIA B
3. VON WILLEBRAND’S DISEASE
Acquired:
1. Anticoagulant therapy
2. Liver diseases
3. DIC
HEMOPHILIA A (Classic Hemophilia)80-85% of all HemophiliacsDeficiency of Factor VIIILab Results - Prolonged PTT
HEMOPHILIA B (Christmas Disease)10-15% of all HemophiliacsDeficiency of Factor IXLab Test - Prolonged PTT
VON WILLEBRAND’S DISEASEDeficiency of VWF & amount of Factor VIIIFactor VIII is bound to vWF while inactive in
circulation; Factor VIII degrades rapidly when not bound to vWF
Lab Results - Prolonged BT, PTT
ANTICOAGULANTS
An anticoagulant is a substance that prevents coagulation; that is, it stops blood from clotting
This prevents deep vein thrombosis, pulmonar embolism, myocardial infarction and stroke.
ANTICOAGULANTS1. Coumadins (Vitamin K antagonists)2. Heparin
Coumadins
These oral anticoagulants that antagonize the effects of vitamin K.
Examples include warfarin. It takes at least 48 to 72 hours for the anticoagulant effect to develop. Where an immediate effect is required, heparin must be given concomitantly.
Monitored by PT times These anticoagulants are used to treat patients
with deep-vein thrombosis (DVT), pulmonary embolism (PE), atrial fibrillation (AF), and mechanical prosthetic heart valves.
Heparin
Heparin is a biological substance. It works by activating antithrombin III, which
blocks thrombin from clotting blood. Heparin Therapy is Monitored by PTT times Low molecular weight heparin is a more highly
processed product that is useful as it does not require monitoring of the APTT coagulation parameter (it has more predictable plasma levels) and has fewer side effects.
Liver Disease
Liver Disease can Result in Reduced Production of Coagulation Factors (I,II,V,VII,IX,X).
DIC
Disseminated intravascular coagulation (DIC is a pathological activation of coagulation) blood clotting) mechanisms that happens in response to a variety of diseases
DIC leads to the formation of small blood clots inside the blood vessels throughout the body
The small clots also disrupt normal blood flow to organs (such as the kidneys), which may
malfunction as a result
As the small clots consume coagulation proteins and platelets, normal coagulation is disrupted and abnormal bleeding occurs from the skin the gastrointestinal tract, the respiratory tract and
surgical wounds. The PT and APTT are usually very prolonged and
the fibrinogen level markedly reduced High levels of fibrin degradation products,
including D-dimer, are found owing to the intense fibrinolytic activity stimulated by the presence of
fibrin in the circulation.
Definitive diagnosis depends on the result of DIC:
Thrombocytopenia) prolonged bleeding time) Prolongation of prothrombin time and activated
partial thromboplastin time A low fibrinogen concentration Increased levels of fibrin degradation products
Platelet count
Bleeding time
Partial thromboplastin time
Prothrombin time
Condition
unaffected prolonged prolonged unaffected Von Willebrand disease
unaffected unaffected prolonged prolongedVitamin K deficiency or Warfarin
unaffected prolonged unaffected unaffected Uremia
unaffected unaffected prolonged unaffected Haemophilia
unaffected unaffected prolonged prolonged Factor V deficiency
unaffected prolonged unaffected unaffected Aspirin
decreased prolonged unaffected unaffected Thrombocytopenia
decreased prolonged prolonged prolonged End-stage Liver failure
decreased prolonged prolonged prolongedDisseminated intravascular coagulation
decreased prolonged unaffected unaffected Bernard-Soulier syndrome
THANK YOU
Recommended