Platelet disorders

Question 1

Define immune thrombocytopenic purpura

Answer 1

Immune destruction of platelets

Question 2

Describe brief pathophysiology of immune thrombocytopenic purpura

Answer 2

IgG antibodies bind to glycoproteins on the platelets and megakaryocytes -> opsonizes them -> phagocytosis

Question 3

Primary causes of immune thrombocytopenic purpura

Answer 3

May follow viral infection/immunisation

Question 4

Secondary causes of immune thrombocytopenic purpura

Answer 4

Occurs in association with some malignancies (CLL) and infections (HIV, Hep-C)

Question 5

Clinical presentation of immune thrombocytopenic purpura

Answer 5

Easy bruising, purpura

Question 6

Diagnosis of immune thrombocytopenic purpura

Answer 6

Thrombocytopenia (decreased platelets)
Increased/normal megakaryocytes in BM
Platelet auto antibodies (in 60-70%)

Question 7

Treatment of immune thrombocytopenic purpura

Answer 7

FIRST LINE = Immunosuppression, e.g. Corticosteroids (such as Prednisolone)
Give platelets
Tranexamic Acid - inhibits fibrin breakdown - not for urinary tract

Question 8

Define thrombotic thrombocytopenic purpura

Answer 8

Spontaneous platelet aggregation in microvasculature, e.g. brain, kidney, heart

Question 9

Pathophsiology of thrombotic thrombocytopenic purpura

Answer 9

Due to a reduction in a protease enzyme (ADAMTS13) -> failure to breakdown high molecular weight VWF -> widespread aggregation and adhesion of platelets -> microvascular thrombosis -> consumption of platelets -> profound thrombocytopenia

Question 10

Causes of thrombotic thrombocytopenic purpura

Answer 10

Autoimmunity (e.g. SLE), Cancer, Pregnancy, Drugs (e.g. Quinine), idiopathic

Question 11

Clinical presentation of thrombotic thrombocytopenic purpura

Answer 11

PENTAD -->
Fever
Microangiopathic haemolytic anaemia
AKI
Neurological symptoms (headache, palsies, seizures, confusion, coma)
Reduced platelets

Question 12

Diagnosis of thrombotic thrombocytopenic purpura

Answer 12

Haematuria/proteinuria

Blood film = fragmented red blood cells, low platelets, low Hb

Question 13

Treatment of thrombotic thrombocytopenic purpura

Answer 13

URGENT PLASMA EXCHANGE = life saving! - Replaces ADAMTS13 and removes antibody
Immunosuppression
Do NOT give platelets –> increases thombosis

Question 14

Define Disseminated Intravascular Coagulation

Answer 14

Cytokine release in response to systemic inflammatory response syndrome (SIRS)

Question 15

Pathophysiology of DIC

Answer 15

Leads to widespread systemic generation of fibrin within blood vessels, caused by initiation of the coagulation pathway.
Either causes:
- Microvascular thrombosis -> organ failure
- Consumption of platelets and coagulation factors -> bleeding -> inhibiting fibrin polymerisation

Question 16

Causes of DIC

Answer 16

Sepsis
Major trauma
Advanced cancer
Obsteric complications
Pancreatitis
Acute promyelocytic leukaemia

Question 17

Clinical presentation of DIC

Answer 17

Bruising, bleeding, renal failure

Bleeding from venepuncture sites and nose/mouth

Question 18

Diagnosis of DIC

Answer 18

Blood films - fragmented RBC's
Thrombocytopenia
Prolonged PT and APTT
Low fibrinogen
High D-dimers

Question 19

Treatment of DIC

Answer 19

If non-bleeding –> Heparin

If bleeding –>

• Platelets
• Fresh Frozen Plasma (FFP)
• Cryoprecipitate
• Red cell transfusion