Thrombocytopenia

Question 1

What is thrombocytopenia?

Answer 1

Low platelet count

Question 2

What is the normal platelet count range?

Answer 2

150-450 x 10^9/L

Question 3

What are the production problems that lead to thrombocytopenia?

Answer 3

Sepsis 
B12 and folate deficiency 
Liver failure - causes failure of thrombopoietin production in the liver 
Leukaemia
Myelodysplastic syndrome

Question 4

What are the destruction problems that lead to thrombocytopenia?

Answer 4

Medications 
Alcohol 
Idiopathic thrombocytopenic purpura
Thrombotic thrombocytopenic purpura 
Heparin induced thrombocytopenia 
Haemolytic uraemic syndrome

Question 5

Which medications can lead to thrombocytopenia?

Answer 5

Methotrexate 
Sodium valproate 
Isotretinoin 
Anti-histamines 
Proton pump inhibitors

Question 6

Presentation of thrombocytopenia

Answer 6

Mild thrombocytopenia incidentally picked up on FBC

Platelet count <50 x10^9/L - spontaneous bruising, prolonged bleeding times - nosebleeds, bleeding gums, heavy periods, easy bruising or blood in urine/stools

Platelet count <10x10^9/L = high risk for spontaneous bleeding, spontaneous intracranial haemorrhage or GI bleeds

Question 7

Differential diagnosis of abnormal/ prolonged bleeding

Answer 7

Thrombocytopenia
Von Willebrand Disease 
Haemophilia A 
Haemophilia B 
Disseminated intravascular coagulation (usually secondary to sepsis)

Question 8

Immune thrombocytopenic purpura is also known as?

Answer 8

Autoimmune thrombocytopenic purpura
Primary thrombocytopenic purpura
Idiopathic thrombocytopenic purpura

Question 9

What is the pathophysiology of ITP?

Answer 9

Antibodies form against platelets –> destruction of platelets –> low platelet count

Question 10

Management of ITP?

Answer 10

Prednisolone
IV immunoglobulins
Rituximab = monoclonal Ab against B cells
Splenectomy

Question 11

What is important in patient education of ITP?

Answer 11

That platelet count requires monitoring
Need to know concerning signs of bleeding e.g. persistent headaches and melaena 
When to seek help 
Carefully controlling BP 
Suppressing menstrual periods

Question 12

What is thrombotic thrombocytopenic purpura?

Answer 12

Clots develop throughout the small vessels of the body - using up platelets and causing thrombocytopenia
It’s a microangiopathy because it affects the small vessels

Question 13

What is the pathophysiology?

Answer 13

Clots form because of a defect in the ADAMTS13 protein

Question 14

What is the normal function of ADAMTS13 protein?

Answer 14

Inactivates von Willebrand factor, reduces platelet adhesion to vessel walls and clot formation

Question 15

What happens in TTP?

Answer 15

Shortage of ADAMTS13 –> von Willebrand overactivity –> clot formation in small vessels –> platelets used up –> thrombocytopenia

Question 16

How does TTP cause additional haemolytic anaemia?

Answer 16

The microclots in the small vessels –> break up RBCs –> haemolytic anaemia

Question 17

What are the causes of deficiency in ADAMTS13?

Answer 17

Inherited genetic mutation OR

Autoimmune disease where antibodies are created against the protein

Question 18

Treatments of TTP?

Answer 18

Plasma exchange
Steroids
Rituximab
guided by haematologist

Question 19

What is heparin induced thrombocytopenia?

Answer 19

Thrombocytopenia by antibodies forming against platelet factor 4 on platelets which occurs as a result of exposure to heparin

Question 20

How does the HIT PF4/heparin antibodies cause thrombocytopenia?

Answer 20

HIT antibodies bind to platelets and activate clotting mechanisms –> causing hypercoagulable state –> thrombosis –> they also break down platelets and cause thrombocytopenia

Question 21

So HIT causes?

Answer 21

Pts on heparin with thrombocytopenia form unexpected clots

Question 22

Diagnosis of HIT?

Answer 22

Testing for HIT antibodies in the patients blood

Question 23

Management of HIT

Answer 23

Stopping heparin

Anticoagulation with an alternative anticoagulant guided by a specialist