These can arise due to decreased bone marrow production, excess destruction or poor functioning

– These abnormalities are divided into quantitative (low platelet count due to bad supply or removal) and qualitative disorders (where there is a problem with the structure or function of the platelet)

– Clinical features usually involve mucosal and skin bleeding.

– Skin bleeding –> leads to petechiae + Purpura (3mm) + Easy bruising.

– Mucosal bleeding –> leads to epistaxis (most common symptom) + GI bleeding + hematuria

Immune Thrombocytopenic Purpura (ITP)

This is an autoimmune production of antibodies directed against platelet antigens, such as the glycoprotein IIb/IIIa or Ib-V-IX complex

– It can be associated with autoimmune haemolytic anaemia – this is called Evan’s syndrome.

– Can be acute –> seen in children weeks after viral infection, but self-limiting and resolves within weeks

– Can be chronic –> Seen in women of childbearing age, primary or secondary to conditions (e.g. SLE)

– IgG antibodies can cross placenta to give thrombocytopenia in offspring for a short time after birth.

Symptoms:

– Purpura and petechiae, especially on the extremities

– Bleeding (Epistaxis and menorrhagia)

Management:

– 1st line corticosteroids (children respond well, but adults may relapse)

– In symptomatic bleeding, give IV immunoglobin to raise platelet count

Microangiopathic Haemolytic Anaemia (MAHA)

This is the pathological formation of platelet microthrombi in small vessels, which consumes up platelets.

– RBCs are sheared as they cross microthrombi, resulting in hemolytic anaemia with schistocytes.

– This can be seen in a few different conditions

Haemolytic Uraemic Syndrome (HUS):

This is a conditions which is seen in children usually after an infective gastroenteritis (food poisoning) episode

– Primary HUS occurs due to complement dysregulation

– Secondary HUS is usually due to Shiga-toxin from E. Coli (STEC) 0157:H7.

– The bacterias produces a toxin damaging endothelium causing excessive platelet aggregation

Thrombotic Thrombocytopenic purpura (TTP)

This is a condition which occurs due to a deficiency of the enzyme which usually cleaves vWF into monomers

– This leads to large, uncleaved vWF giving abnormal platelet adhesion, resulting in microthrombi

– It can be congenital or due to an acquired autoantibody, more commonly in adult females

Symptoms:

– Haemolytic Anaemia

– Thrombocytopenia (giving bleeding with purpura and epistaxis)

– AKI

– Fever

– Neurological features e.g. headache, seizures

Management:

A haematological emergency –> Plasma exchange (removes antibodies) + Steroids