Transcript VWF:Ag

Coagulation Cascade
Amplification
Initiation
Introduction
• Congenital bleeding disorder caused by
low levels of specific coagulation factors
• Hemophilia A: 85%, factor VIII deficiency
Third most common X-linked disorder
• Hemophilia B: 10%-15%, factor IX
deficiency
Genetics
• X-linked recessive disorder
• FVIII gene is on Xq28; most common (45%)
defect is inversion and translocation of exons 122 away from 23-26, others: point mutation
• 1/10,000 live male births
• 女性也可能為symptomatic carriers (ex. extreme
“Lyonisation” of the normal X chromosome)
• 約1/3為mutation
Classifications
依血液中凝血因子的剩餘含量而定
• Severe: < 1 unit/dL (1% activity)
• Moderate: 1%-5%
• Mild: > 5%
Definition
• 1 unit = the amount found in 1ml of normal pool plasma
• 100% activity = the actvity found in 1ml of normal pool
plasma
Bleeding Manifestations in
Hemophilia
Sites of bleeding
• Serious
Joints (hemarthrosis), muscle/soft tissue,
mouth/gum/nose, hematria
• Life-threatening
CNS, GI, neck/throat, severe trauma
• Incidence of different sites of bleeding
Hemarthrosis: 70-80%
Muscle/soft tissue: 5-10%
CNS: <5%
Clinical Manifestations
• 嚴重者，出生時就可能出現subgaleal
hematoma and/or ICH〈應特別留意嬰兒室
頭圍迅速增大的新生兒〉
• 症狀可能多在開始爬及走路時才出現
• The hallmark of hemophilic bleeding:自發
性的關節出血 (hemarthrosis) and
intramuscular hematoma
• 1-2 % ICH
其他出血的警訊
• 腦出血：infants with “meningitis”
• 後腹腔出血：嚴重腹痛，可能誤為盲腸炎
• 頸部、咽喉出血：喉痛、吞嚥困難，可能
阻塞呼吸道
• Toddler: ankle most, than knee
• Child: knee most, than ankle
Diagnosis and Laboratory Tests
•
•
•
•
•
•
Family history
Normal platelet count, bleeding time, PT
Prolonged PTT
Specific factor assays
Genetic testing
Prenatal diagnosis
Management
• History of hemophilia treatment
Decade
Milestone (s)
1840s
First transfusion administered
1940s
Transfusion therapy estabilished
1950s
FFP; early factor concentrates
1960s
Cryoprecipitate
1970s
Intermediate-purify factor concentrates; DDAVP
1980s
Monoclonal antibody-purified and high-prify factor VIII
concentrates; effective viral inactivation
1990s
High-purify factor IX concentrates; recombinant factor
VIII and IX threapy
2000s
Improved recombinant products; gene therapy ?
治療
• A型： FFP，cryoprecipitate 或 factor VIII
concentrate
(dose: desired rise level % × BW × 0.5)
• B型：FFP或factor IX concentrate
(dose: desired rise level % × BW × 1.2~1.5)
• Factor concentrate: plasma-derived or
recombinant product
• DDAVP for mild or moderate form
• Antifibrinolytic therapy
On-demand Therapy
• 一有症狀出現就及早注射（即補充）凝血
因子
• 劑量及次數視體重、病情輕重、出血程度
及出血部位而定
Recommeded Plasma Factor Level
and Duration of Administration
Type of
hemorrhage
Hemophilia A
Hemophilia B
Desired
level
Duration
(days)
Desired
level
Duration
(days)
Joint
40-60%
1-2 or longer
40-60%
1-2 or longer
Muscle
40-60%
2-3 or longer
40-60%
2-3 or longer
Initial
80-100%
1-2
60-80%
1-2
Maintenance
30-60%
3-5 or longer
30-60%
3-5 or longer
80-100%
1-7
60-80%
1-7
50%
8-14
30%
8-14
Iliopsoas
CNS/head
Initial
Maintenance
Type of
hemorrhage
Hemophilia A
Hemophilia B
Desired level
Duration (d)
Desired level
Duration (d)
80-100%
1-7
60-80%
1-7
50%
8-14
30%
8-14
80-100%
1-6
60-80%
1-6
Maintenance
50%
7-14
30%
7-14
Kidney
50%
3-5
40%
3-5
Throat and
neck
Initial
Maintenance
GI
Initial
Surgery (major)
Pre-op
80-100%
Post-op
60-80%
40-60%
30-50%
60-80%
1-3
4-6
7-14
40-60%
30-50%
20-40%
1-3
4-6
7-14
Prophylactic Therapy
• 原理：將重度缺乏者的凝血因子提升至
>1%
• 有效減少自發性出血
• 避免關節出血及進一步關節病變
• 瑞典最早開始， A型血友病自1958年起，B
型血友病自1972年起
Prophylaxis
• Initial observation: persons with moderate
hemophilia (1-5% FVIII) have decreased joint
disease
• Hypothesis: converting a person from severe
hemophilia to moderate with prophylaxis would
decrease incidence of joint disease
• Goat: to raise FVIII above 1% was commenced
in Malmo, Sweden in 1958
• Lovqvist, et al: J Intern Med 1997
When to Start: The Swedish
Experience
Conclusion: prophylaxis should be started in the first years of life,
before age 3
Astermark et al: Br J Hematol 1999
一般照護
• 預防注射: 最小的針頭接種
• 不可接受其他肌肉注射
• 勿吃含有阿斯匹靈的止痛藥， 但Panadol,
Ponstan, Codeine可以服用
• 牙齒的保護
長期的關節病痛問題
• Target joints: 膝關節、踝關節及肘關節
• 惡性循環下，發生慢性關節炎
• Arthropathy: most significant chronic
morbidity
• 預防是最佳的處理方法
• Arthroscopic synovectomy
• Joint replacement
輸血引發的感染
• 經加熱等特殊程序處理血液製品後，1985
年以後出生的血友病患者，至今並無因注
射凝血因子而感染愛滋病的報告
• HBV, HCV infection
(vaccination using is recommended)
• Recombinant product可完全免除這種潛在
的危險
凝血因子抗體
• 14-25% of severe hemophilia A, very rare
in hemophilia B
• 可能與基因有關
• 輕者可能需要大量而頻繁的注射才可能止
血
• 嚴重的就可能對注射凝血因子無效，必須
使用其他凝血因子 (by-pass)
What are inhibitors ?
• Antibodies directed against coagulation factors
Alloantibody in patients with hemophilia A or B
Autoantibody in people without hemophilia
• Incidence
Antifactor VIII inhibitors in hemophilia A: 25%
Antifactor IX inhibitors in hemophilia B: 1-3%
Antifactor VIII autoantibody inhibitors: 1/106/year
• Usually result in loss of coagulation factor
function
Factor VIII inhibitors
• The most common inhibitor
• Polyclonal IgG antibodies, esp IgG4
• Bleeding is more severe in autoantibody
patients than in hemophilia A inhibitor
patients
Etiology
Definite Factors Involved
• FVIII gene mutation
No FVIII protein means high risk
• Adjuvants in FVIII products
• Race
Higher in African-Americans
• HLA status
• Immune modifiers
IL10 polymorphism
Classification of Inhibitors
Definitions
• “High” responders
IgG inhibitors of titer > 5 Bethesda Units (BU)
Inability to overwhelm with native factor
• “Low” responders
< 5 BU
Transient
Less likely to have anamnestic responses
Amenable to treatment by overwhelming
inhibitor with native factor VIII or XI
Treatment Options for Highresponder Inhibitors
Bypassing agents
• Low-purity, plasma-derived concentrates
Prothrombin complex concentrates
Activated prothrombin complex concentrates
Recombinant VIIa
• Emergency treatments
Recombinant VIIa
Plasmapheresis
Porcine VIII and new recombinant procine VIII
Treatment Options for Highresponder Inhibitors
• Immune tolerance induction
• Rituximab
Anti-CD20 chimeric antibody reliably depletes
peripheral B cells
Several reports of success in acquired
hemophilia (an autoimmune disorder)
NHLBI-sponsored clinical trial through
Transfusion Medicine/Hemostasis research
network to begin May 2006
• Fox et al, Hemophilia 2006
von Willebrand Disease
• Disorder first described by Erik von Willebrand in
1925 in persons living off the coast of Finland
• Marked heterogeneity in phenotype, autosomal
Dominant or Recessive Inheritance
• Deletion in chromosome 12 is most common
• Overall prevalence 1:100 to 1: 500
• Incidence equal among Man and Women
(chromosome 12)
1994 Classifications of VWD by TSTH
1994
Term
1994 Definition
Genetics, Comment
Type 1
Partial quantitative deficiency
Dominant with variable expression;
phenotype influenced by multiple genes
Type 2
Qualitative defect
Type 2A
Decreased platelet-dependent function
with absence of largest multimers
Dominant
Type 2B
Increased VWF affinirty for platelet GPIb
Dominant. May be associated with
thrombocytopenia, especially after DDAVP
Type 2M
Decreased platelet-dependent function
with presence of largest multimers
Dominant
Type 2N
Decreased VWF affinity for FVIII
Recessive, often mistaken for mild-moderate
hemophilia A
Type 3
Virtually complete deficiency
Recessive: homozygous or doubly
heterozygous
Platelet-type
(pseudo-VWD)
Not a defect of VWF, not to be
considered a form of VWD
Dominant. A platelet disorders: increased
affinity of platelet GPIb for VWF.
Thrombocytopeinia may be present.
vWF Genetics
Location of Gene: chromosome 12 (p13.3)
• http://www.vwf.group.shef.ac.uk/pictures.html
vWF Protein
•
•
•
•
A1: binds to Gp IB alpha
A3: Collagen binding Domain
D’/D3: Interacts with Factor VIII
C2: Interacts with GpIIb/IIIa
• http://www.vwf.group.shef.ac.uk/pictures.html
vWF Protein
• A1: type 2B and 2M
• A2: type 2A, cleavage site for ADAMTS 13
• D’/D3: type 2N
• http://www.vwf.group.shef.ac.uk/pictures.html
Diagnosis
vWD Tests: Initial Work-up
•
•
•
•
•
•
Quantitative
Factor VIII level
vWF Antigen level
vWF Multimers
Qualitative
Ristocetin Cofactor Assay: studies function
of Vwf/Platelet interaction
Lab Values in vWD Subtypes
Variants of vWD
Official Abbreviated Terms as Designated by ISTH
Factor VIII
Von Willebrand factor
Type of Test
Official Old or
informal
Immunological
(total amount,
functional or not)
FVIII:Ag FVIII:CAg VWF:Ag
FVIII
Functional
(functional assay)
FVIII:C,
AHF,
AHG
Official
VWF:RCo
(ristocetin cofactor)
VWF:CB
(collagen binding)
VWF:FVIIIB
(factor VIII binding)
ISTH: International Society on Thrombosis and Hemostasis
Old or
informal
FVIIIR:Ag
AHF:Ag
FVIIIR:RCo
and others
VWF:CBA
Differential Diagnosis
Hemophilia A & von Willebrand Disease
Management
• Education
• Cryoprocipitate
(dose: desired rise level % × BW × 0.75)
• DDAVP for type 1
• Amicar (antifibrinolytic agent) for mucosal bleeds
• Humate-P (factor 8 and vWF) for surgery,
trauma
• Platelet for pseudo-vWD
• Recombinant factor 7a, correct underlying
disorder (hypothyroidism) for acquired vWD
Platelet
Platelet Anatomy
•
•
•
•
Disc-shaped, anuclear fragment
Size: 1.5 μm
Normal maturation time 4-5 days
Circulating life span 9-10 days
Platelet Anatomy
• Peripheral zone
Plasma membrane
Open canalicular system
Extension of the plasma membrane
Forms interconnecting network, greatly increases the
surface area
Membrane proteins: receptors for agonists and
adhesive glycoproteins, signal transduction molecules
IIb-IIIa: fibrinogen, vWF, fibronectin
Ib-IIa: collagen
Ib-IX-V: insoluble Vwf
VI: collagen
Platelet Anatomy
• Submembranous zone
Contractile protein system: regulates shape
and carry out events such as secretion of
granules and retraction of clots
• Organelle zone
Platelet specific storage granules
Dense bodies: serotonin, ADP, ATP, Ca
α granules: platelet factor 4, thromboglobulin,
PDGF, vWF
Lysosomes, peroxisomes
Hemostasis: Adhesion
• Initial event in hemostasis
• Platelets contact subendothelial components
exposed after vessel injury
• vWF secreted into extracellular matrix from
endothelial cells binds to GPIb-V-IX on platelet
surface
• vWF on endothelial cells forms a bridge between
the subendothelium and platelet
Hemostasis: Activation
• Interaction between GP Ia-IIa and GP VI
with collagen results in platelet arrest and
activation
• Forms a firm adherence
• Leads to intracellular signaling processes
that initiate secretion
• Activated platelets express a procoagulant
surface
Hemostasis: Secretion
•
•
•
•
•
•
Undergo shape change
Spherical
Pseudopods
Spread over the exposed subendothlium
Contents of platelet granules are released
α granules: fibrinogen, vWF, thrombospondin,
factor V, vitronectin
• Dense granules: ADP, ATP, serotonin, calcium
Hemostasis: Aggregation
• Once activated, platelets become
adhesive to each other
• Interact via fibrinogen bound to their
GPIIb-IIIa receptors
• Microthrombus of aggregated platelets is
formed
Presentation of Disorders of
Platelet Function
•
•
•
•
•
•
•
•
Mucocutaneous bleeding
Gingiva
Epistaxis
Menorrhagia
Petechiae
Ecchymoses
Bleeding after trauma and surgery
Rare: ICH, joint, muscle
Clinical Presentation of
Bleeding Disorder
Clinical signs
Disorders of
coagulation
Disorder of platelets
or vessles
Petechiae
Rare
Characteristics
Ecchymoses
Common, large
Characteristics,
small
Bleeding from
superficial cuts
Minimal
Persistent
Delayed bleeding
Common
Rare
Deep hematomas
Characteristics
Rare
Hemothrosis
Characteristics
Rare
Diagnostic work up
•
•
•
•
•
•
•
•
•
Initial
Platelet count and morphology
PT, PTT (mixing studies)
Platelet function analyzer (PFA)-100
Bleeding time
vWD panel
Platelet aggregation
Flow cytometry, electron microscopy
Detailed drug history
Inherited Platelet Function
Disorders
• Adhesion
Bernard Soulier Syndrome
Collagen receptor deficiency
• Aggregation
Glamzman’s Thrombasthenia
• Secretion
Storage pool disorders
• Coagulant activity
Scott syndrome
Bernard-Soulier Syndrome
•
•
•
•
•
•
•
•
First described in 1948
AR
Present in infancy or early childhood
Thrombocytopenia, giant platelets, bleeding
tendency
Abnormality of the GP Ib-IX-V complex
Normally binds to vWF
Initial platelet adhesion to the subendothelium
Mutations in Ibα, Ibβ, or IX
Bernard-Soulier Syndrome
•
•
•
•
•
Prolonged bleeding time
Thrombocytopenia, variable
Abnormal smear, enlarged platelets
Aggregation
Normal in response to ADP, epinephrine,
arachadonic acid, collagen
• Fails in response to ristocetin
• Cannot be corrected by the addition of normal
plasma containing vWF
• Abnormal flow cytometry
Glanzmann Thrombasthenia
• First described in 1918
• AR
• Present with mucocutaneous bleeding as
neonate or infant
• Bleeding tendency, normal platelet count
• Deficiency of GPIIb/IIIa
• Normally binds to fibrinogen and vWF
• Cross links adjacent platelets to form platelet
plug
Glanzmann Thrombasthenia
•
•
•
•
•
•
•
Normal platelet count and morphology
Prolonged bleeding time
PFA-100
COL/EPI abnormal
COL/ADP abnormal
Aggregation
Abnormal in response to all agonists except
ristocetin
• Flow cytometry abnormal
Storage Pool Disorders
Gray Platelet Syndrome
•
•
•
•
•
•
•
•
•
Absence of αgranules (normal ~ 50)
AR
Molecular defect unknown
Mild mucocutaneous bleeding
Variably prolonged bleeding time
Moderate thrombocytopenia
Reticulin fibrosis of BM
Large gray platelet
EM: small, empty or absent αgranules
Storage Pool Disorders
Dense Granule Disorders
•
•
•
•
•
•
Normal dense granules
3-6/platelet
Serotonin, ADP, ATP, Ca
Heterogeneous group of disorders
Molecular defect unknown
Mild to moderate bleeding
Storage Pool Disorders
• Two autosomal recessive syndromes
associated with albinism
Chediak-Higash
Hermansky-Pudlack
• Non-albino syndromes
Wiskott-Aldrich
Thrombocytopenia absent radii
Osteogenesis imperfecta
Storage Pool Disorders
Chediak-Higash
• Partial oculocutaneous
albinism
• Frequent pyogenic
infection
• Giant lysosomal granules
in cells
• Thrombocytopenia
• Dense granule deficiency
Hermansky-Pudlack
• Oculocutaneous albinism
• Inclusions in the cells of
RES
• Thrombocytopenia
• Dense granule deficiency
• Common in Puerto Rico
Storage Pool Disorders
•
•
•
•
•
Clinical presentation
Platelet morphology normal
Bleeding time usually, not always prolonged
Aggregation
Marked impairment with weak agonists ADP,
epinephrine and low concentrations of collagen
• Response to higher concentration may be
normal
• Absent second wave of aggregation when
stimulated by ADP and epinephrine
Disorders of Procoagulant Activity
Scott syndrome
• AR
• Severe bleeding
• Decrease transport of phospholipids to surface
of activated platelet
• Decreased expression of factor Xa binding sites
• Failure of factor Xa to bind
• Incapacity of the activated cell surface to
transform prothrombin to thrombin
• Prothrombin consumption test is the only
abnormal test
Thrombocytopenia
• Increase platelet destruction
Immune
Non-immune
• Decreased platelet production
Congenital
Acquired
• Sequestration
• Qualitative platelet disorders
Qualitative Platelet Disorders
• Wiskott-Aldrich syndrome
X-linked; small platelet
• Bernard-Soulier syndrome
AD, large platelets
• May-Hegglin anomaly
AD, giant platelet, Dohle bodies
• Gray platelet syndrome
Pale/oval platelet
• Glandzmann’s thrombesthenia
Sequestration
• Kasabach-Merritt syndrome
• Hypersplenism
May be associated with infiltrative disease
(leukemia)
May arise from liver disease, portal hypertension
• In Vitro platelet clumping
• Easily diagnosed by peripheral smear evaluation
Decreased Platelet Production
Congenital
• Thrombocytopenia-Absent Radius syndrome
Absence of radii at birth
Association with congenital heart disorder
• Amegakaryocytic Thrombocytopenia
Presents in neonatal period
No skeletal anomalies
• Fanconi Anemia
Due to aplastic anemia
Short stature, thumb and radii hypoplasia,
microcephaly
Thrombocytopenia-Absent Radius
Decreased Platelet Production
Acquired
•
•
•
•
•
•
•
Leukemia
Aplastic anemia
Neuroblastoma
Due to bone marrow metastasis
Drugs
Nutritional deficiency
Megaloblastic anemia
Increased Platelet Destruction
Nonimmune
• Hemolytic-uremic syndrome
Microangiopathic anemia
Bloody diarrhea (E coli O157:H7)
• Disseminated intravascular coagulation
Microangiopathic anemia; low fibrinogen
Sepsis
• Cyanotic heart disease
Increased Platelet Destruction
Immune
•
•
•
•
•
•
HIV
Post transfusion
Drugs
Collagen-vascular disease
Neonatal alloimmune thrombocytopenia
Idiopathic thrombocytopenia
Heparin and Thrombocytopenia
• Immune Heparin-induced thrombocytopenia
• Initially presents as decrease in platelet with or
without thrombosis
• Two distinct syndromes:
• 1 Uaually mild and transient thrombocytopenia
with rapid recovery upon discontinuation of
heparin
• 2 Severe thrombocytopenia often complicated
by thrombosis or DIC
Neonatal Thrombocytopenia
Child born to Mother with
ITP
• Mother with
thrombocytopenia
• Resolves within about 6
weeks
• Risk of ICH 1%
• Avoid maternal platelet
transfusion
Neonatal alloimmune
thrombocytopenia
• Mother with normal
platelet
• Resolves with about 6
weeks
• Risk of ICH 10-30%
• Maternal platelet
transfusion for bleeding
• Severity increases with
subsequent siblings
Idiopathic Thrombocytopenia
Purpura
• Diagnosis is based primarily on the history, PE,
CBC, and peripheral smear examination
• CBC must show isolated and usually severe
thrombocytopenia
• Bone marrow aspiration should be performed in
patients with thrombocytopenia lasting more
than 6 to 12 months, and in those unresponsive
to IVIG therapy
Idiopathic Thrombocytopenia
Purpura
•
•
•
•
•
•
•
•
•
Clinical features
M=F
Child is well with rapid onset of thrombocytopenia
Generally seen in children 1 to 9 years old
Peak incidence is between 2 to 5 y/o
1 in 1500 persons with get ITP in childhood
Seasonal presentation
More common in winter and fall
Platelet-specific autoantibodies seen 4-8 weeks following
a viral illness or exposure
ITP Treatment
•
•
•
•
•
•
•
•
•
•
Severe life-threatenin bleeding
IVIG, steroids, platelet transfusion
Platelet counts > 30k
Asymptomatic or only minor purpura: no treatment
Platelet counts < 20k
Significant mucosal bleeding
Treatment with IVIG or steroids
Platelet counts < 10k
Only minor purpura
Treatment with IVIG or steroids
ITP Treatment
• IVIG
• More rapid increase in platelet counts
• The mean platelet count in the IVIG group was
approximately 2.5 times than steroid gr
• Average platelet count rose over 30k by 24 hrs
in IVIG, and by 48 in steroid gr. At one week the
levels were equal
• IVIG will not affect subsequent BM biopsy
results
• Dosing: 1g/k on 1 day
ITP Treatment
• Steroids
• IVIG costs about 150 times as much as
treatment with steroids
• IVIG can cause aseptic meningitis
• Causing an emergent diagnostic
evaluation to rule out ICH
• Dosing: 2mg/k/day
Chronic ITP
• Defined as thrombocytopenia lasting
longer than 6 months
• Child may present with recurrent upper an
lower respiratory tract infections, GERD,
and FTT
• Family history is often positive for ITP or
other autoimmune disease (SLE)
Acquired Platelet Defects
• Medications
• Chronic renal failure
• Abnormal platelet aggregation, reduced
secretion in response to many agonists
• May be caused by both dialyzable and
nondialyzable substances
• Cardiopulmonary bypass surgery
• SLE
• Chronic myeloproliferative disorders and acute
leukemia
DIC
Clinical Conditions
Associated with DIC
•
•
•
•
•
Sepsis/severe infection (any microorganism)
Trauma (polytrauma, fat embolism)
Organ destruction (severe pancreatitis)
Malignancy (solid tumors, hematological malignancy)
Obstetrical calamities (amniotic fluid embolism, abruptio
placentae)
• Vascular abnormalities (Kasabach-Merritt syndrome,
large vascular aneurysms)
• Severe hepatic faliure
• Severe toxic or immunologic reactions (snake bites,
transfusion reactions, transplant rejection)
Pathogenesis:
Initiation of Fibrin Deposition
Hambleton, J. et al. Hematology 2002
Pathogenesis:
Amplification of Fibrin Deposition
Hambleton, J. et al. Hematology 2002
Pathogenesis:
Amplification of Fibrin Deposition
Hambleton, J. et al. Hematology 2002
Pathogenesis:
Propagation of Fibrin Deposition
• Fibrinolytic system is downregulated at the time of max.
activation of coagulation
• In baceremia, endothelial cells release plasminogen
activators
• Increase plasminogen activator inhibitor, type 1 (PAI-1)
immediately to suppress of fibrinolytic activity
• High PAI-1 level strongest predictors of mortality (ref 3)
• 4G/5G polymorphism, functional mutation of PAI-1 gene
indicated higher PAI-1, increased risk of death in
bacteremia (ref 38)
Diagnosis
• 1 Underlying disorder
• 2 Global coagulation tests (platelet; PT;
fibrinogen; FDP)
Platelet ()
FDP
PT (sec.)
Fibrinogen (g/L)
Score 0
> 100
1
< 100
2
< 50
No increase
<3
>1
Moderate
3-6
<1
Strong
>6
• If score ≧ 5: DIC, repeat daily
• If score < 5: non-overt DIC, repeat next 1-2 days
Management
• 1.Plasma and platelet substitution therapy
• Only in active bleeding, requiring an
invasive procedure, at risk for bleeding
complications
• 2.Anticoagulants
• 3.Restoration of anticoagulant pathways