徐建民－特发性血小板减少性紫癜.ppt

DISORDERS OF HEMOSTASIS
Hematology ZhongShan Hospital,FuDan University
Prof. JlAN-MIN XU
General Considerations
Disorders of hemostasis
defects in platelet number or function
problems in fibrin clot (coagulation)
Bleeding due to platelet disorders is typically mucosal or dermatologic
include epistaxis, gum bleeding, menorrhagia, gastrointestinal bleeding, purpura, and petechiae
Thrombocytopenic Purpura
Hematology ZhongShan Hospital,FuDan University
Prof. JlAN-MIN XU
Brief
:bleeding of skin、mucous and
organs
:
(1)production :drug, tumor, infection,
radiation
(2)destruction :ITP,DIC,TTP
(3)abnormal distribution:splenomegaly
:primary ,secondary
IDIOPATHIC (AUTOIMMUNE) THROMBOCYTOPENIC PURPURA (ITP)
General Considerations
ITP is an autoimmune disorder in which an IgG autoantibody is formed that binds to platelets
It is not clear which antigen on the platelet surface is involved.
Although the antiplatelet antibody may plement, platelets are not destroyed by direct lysis
General Considerations
Rather, destruction takes place in the spleen, where splenic macrophages with Fc receptors bind to antibody-coated platelets
Since the spleen is the major site both of antibody production and platelet sequestration, splenectomy is highly effective therapy
General Considerations
:thrombocyte unrelated to a drug, an infection, or autoimmune disease is generally classified as ITP
:
shortened span of platelet
increased megakaryocyte in bone marrow
:acute, chronic
Mechanism

(1)acute:
postviral infection
plex (viral Ag and Ab)
connect with platelet Fc-R
ponents banding with platelet
auto Ab generation

(2)chronic:not affected by foreign Ag
Mechanism
and spleen:
(1)1/3 platelets are held within the spleen
(2)spleen produces platelet associated Ab
(3)liver and spleen erase platelet:7-11 days
in normal persons, 1-3 days in patients