Increased losses- sequestration (normally, 1/3 of platelets are sequestered, but in splenomegaly up to 90% can be trapped
Due to portal hypertension
Based on absence or presence of other diseases
Primary
Secondary
Based on patient age
Adult
Child
Based on duration of thrombocytopenia
Acute
Chronic
Immune thrombocytopenic purpura (ITP)
Definition
Autoimmune disease characterized by a low platelet count, purpura, and hemorrhagic episodes caused by antiplatelet autoantibodies
Etiology
Acute
Following vaccination
Following infection
Chronic
Seen in women ages 15-50!
Idiopathic
Association with other diseases- SLE, HIV, CLL, H.pylori infection, HL, autoimmune hemolytic anemia
Forms
Acute
Chronic
Pathogenesis
Platelet autoantibodies, usually IgG, result in the premature removal of platelets from the circulation by macrophages of the reticuloendothelial system
Especially the spleen!
Antibody is directed against the glycoprotein IIb/IIIa or Ib complex
Lifespan of platelet is reduced from 10 days to a few hours!
Symptoms
Petechial hemorrhage
Easy bruising
Menorrhagia
Mucosal bleeding in severe cases
Chronic ITP tends to relapse and remit spontaneously
Has an insidious onset!
Diagnosis
The platelet count is usually 10–100*10^9/L
Normal is 140-440*10^9/L
Blood film- reduced platelets
Bone marrow- normal or increased numbers of megakaryocytes
Sensitive tests- show specific anti-glycoprotein GPIIb/IIIa or GPIb antibodies on the platelet surface or in the serum
