Thrombocytopeania

Question 1

What are the causes of thrombocytopenia?

Answer 1

Impaired platelet production in the bone marrow

Increased platelet turnover in the periphery

Redistribution, dilution and other causes

Question 2

What are some reasons for impaired platelet production in the bone marrow?

Answer 2

Bone marrow failure - aplastic anaemia, paroxysmal nocturnal haemoglobinuria

Bone marrow suppression - drugs, chemo, radiation

Congenital thrombocytopenias - alport syndrome

Infection - EBV, hepatitis C, HIV, mumps, rubella

Malignancy - leukaemia, lymphoma, bone marrow infiltration

Nutritional deficiency - vitamin B12 deficiency/folate deficiency (eg in chronic alcohol abuse)

Other - necrotising enterocolitis

Question 3

What are some causes for increased platelet turnover in the periphery?

Answer 3

Immune thrombocytopenia

Drug induced immune thrombocytopaenia
DIC and sepsis
Infection
Thrombotic thrombocytopaenic purpura
Pregnancy - preeclampsia
Post transfusion thrombocytopaenia

Question 4

Which drugs are most likely to cause drug induced immune thrombocytopenia?

Answer 4

Sodium channel blockers

Calcium channel blockers

Antibiotics

Antiviral agents

Anti thrombotic agents

Question 5

What can cause redistribution, dilution problems to cause thrombocytopenia?

Answer 5

Liver disease and chronic alcohol abuse
Splenomegaly
Gestational thrombocytopenia

Question 6

What is the platelet count and symptoms for mild thrombocytopenia?

Answer 6

Platelet count - >70,000-149,000/ cubed

Symptoms - asymptomatic

Question 7

What is the platelet count and symptoms for moderate thrombocytopenia?

Answer 7

Platelet count - 20,000-70,000/ mm cubed

Symptoms - prolonged bleeding following surgery or trauma
Easy bruising
Occasionally - petechia and purpura

Question 8

What is the platelet count and symptoms for severe thrombocytopenia?

Answer 8

Platelet count - <20,000/mm cubed

Symptoms - spontaneous bruising (ecchymoses), petechia, purpura
Bleeding from the mucosa (eg bleeding gums)
Increased risk of spontaneous life threatening bleeding

Question 9

How do you diagnose someone for thrombocytopenia?

Answer 9

CBC and investigate for the underlying causes with thorough history and routine lab results
Coagulation studies
Peripheral blood smear
Renal function tests
Liver chemistries

Question 10

What will the CBC show for thrombocytopenia?

Answer 10

Decreased platelet count (<150,000/mm cubed) depending on aetiology, anemia or pancytopenia (decrease in number of all cell lines in blood eg erythrocytes, leukocytes, platelets)

Question 11

What will coagulation studies show for thrombocytopenia?

Answer 11

Increased bleeding time

Question 12

What is the differential diagnosis for thrombocytopenia?

Answer 12

Pseudothrombocytopenia
Dilutional thrombocytopenia

Question 13

What is pseudothrombocytopenia?

Answer 13

A spuriously low platelet count due to platelets clumping in vitro

Question 14

What is dilutional thrombocytopenia?

Answer 14

Falsely low plate concentration due to volume overload (too much fluid - hypervolemia)

Question 15

What is the treatment for thrombocytopenia?

Answer 15

All patients - treat any significant bleeding.
Treat underlying cause eg DIC.

Consider empiric treatment (without precise knowledge) for ITP (immune thrombocytopenic purpura) if platelet count is <30,000/mm cubed

If mildly symptomatic or asymptomatic patients with platelet count <50,000/mm cubed / consult haematology

Asymptomatic patients with platelet count >50,000/mm cubed - repeat CBC in 1-4 weeks or if patient becomes symptomatic

Question 16

What are the indications for emergency management of thrombocytopenia?

Answer 16

Neurological symptoms
Anticipated urgent surgery or invasive procedures
Significant bleeding

Question 17

What is the treatment for emergency management of thrombocytopenia?

Answer 17

If there is bleeding - attempt haemostatic control
Urgently replace platelets - platelet transfusion, administer IVIG if an immune cause is suspected