Platelet Disorders

By : Saja Al-Oran

Introduction• The platelet arise from the fragmentation of the cytoplasm of

megakaryocyte in the bone marrow .

• circulate in the blood as disc-shaped anucleate particlesfor 8-10 days.

• Platelets are responsible for primary hemostaticfunction

• Normal count is 150,000 – 400,000/mL .

Quantity Disorders :

• 1-Thrombocytopenia : platelet count <150,000• causes :• 1. Decreased production• 2. increased destruction : (most common cause ) a.immune (ITP,

HIT,SLE) b.non-immune (DIC,TTP)• 3. Sequestration from splenomegaly• 4. Dilutional—after transfusions or hemorrhage

Causes :

CONT….

• Spontaneous bleeding occur when the platelet count fallsbelow 20 × 10^9/L .

• Thrombocytopenia (< 10 × 10^9/L) may result in retinalhaemorrhage and potentially fatal intracranial bleeding, but thisis rare.

Clinical feature :

• Cutaneous bleeding ; petechiae (<2mm) , purpura(2-10mm) , ecchymosis (>10 mm)

• Splenomegaly .• Mucosal bleeding: epistaxis, menorrhagia, hemoptysis,

bleeding in GI, genitourinary .• Excessive bleeding after procedures or surgery.• Gingival bleeding .

Investigation :

• CBC ( decrease platelet count )• Bleeding time, PT , PTT• Peripheral smear

Treatment :

• 1. Treat the underlying cause.• 2. Platelet transfusion—use depending on the cause and

severity of thrombocytopenia.• 3. Discontinue NSAIDs, other antiplatelet agents, and

anticoagulants.

Idiopathic Thrombocytopenic Purpura (ITP) :

• (ITP) : is mediated by autoantibodies, most often directed against the platelet membraneglycoprotein IIb/IIIa, resulting in premature removal of platelet from the circulation bycells of the reticulo-endothelial system .

• The presentation depends on the degree of thrombocytopenia. (Spontaneous bleeding<20 × 10^9/L ).

• In adults, ITP more commonly affects females .• Patients aged over 65 years should have a bone marrow examination to look for an

accompanying B cell malignancy .• IN ITP , peripheral blood film normal , greatly reduced platelet count , increase in

megakaryocytes

Management of ITP :

• Many patients with stable compensated ITP and a platelet count of morethan 30 × 109/L do not require treatment to raise the platelet count,except at times of increased bleeding risk, such as surgery .

• First-line therapy for patients with spontaneous bleeding withprednisolone 1 mg/kg daily .

• Second-line therapy : thrombopoietin receptor agonist (TPO-RA)eltrombag and romilpoistim ,and splenectomy .

Other causes of thrombocytopenia :

• Thrombotic thrombocytopenia purpura (TTP) : widespread clots , renalmalfunction , sheared RBC’s on smear .

• Heparin induced thrombocytopenia (HIT) : recent history ofcommencement of heparin , widespread thrombosis possible .

• Disseminated intravascular coagulation (DIC) :fulminant infection signs ,pregnant ,always increase PT/PTT .

Thrombocytosis :

• 2-Thrombocytosis : (high platelet count) The most common reason it is reactiveto another process such as infection, connective tissue disease, malignancy, irondeficiency,acute haemolysis or gastrointestinal bleeding .

• The presenting clinical features are usually those of the underlying disorder andhaemostasis is rarely affected.

• Reactive thrombocytosis is distinguished from the myeloproliferative disordersby the presence of uniform small platelets, lack of splenomegaly, and thepresence of an associated disorder.

Cont…

Quality Disorders :

• 1-Von Willebrand’s Disease (vWD) : autosomal dominant condition ofdeficient vonWillebrand’s factor , sometime associated with FVIIIdeficiency .

• Clinical feature : ( epistaxis ,bruising , gingival bleeding ,petechiae ,etc)• Labs : bleeding time elevated , PT & PTT (normal ) , platelet count normal .• Ristocetin platelet test .• Treatment : supportive ( iron replacement) , DDAVP (desomopressin ),

platelet transfusion if necessary .

• 2-Bernard-soulier syndrome : autosomal recessive condition of abnormalGp1b expression .

• Clinical feature : ( epistaxis ,bruising , gingival bleeding ,petechiae ,etc)• Labs : bleeding time elevated , PT & PTT (normal ) , platelet count low** .• Ristocetin platelet test.• Treatment : supportive (avoid antiplatelet) , platelet transfusion if

necessary .

• 3-Glanzmann’s thrombasthenia : these conditions are mild disorders, withbleeding typically occurring after trauma or surgery but rarely spontaneously , itis autosomal recessive condition of abnormal GpIIb/IIIa .

• Clinical feature : (menorrhagia ,bruising , gingival bleeding , epistaxis ,etc)• Labs : bleeding time elevated , PT & PTT (normal ) , platelet count normal .• Ristocetin platelet test.• Treatment : supportive (avoid antiplatelet) , platelet transfusion if necessary .

Thank you l