Haematology - Immune Thrombocytopaenic Purpura

Question 1

Definition

Answer 1

Autoimmune disorder = platelets are destroyed by antibodies , leading to low platelet counts and an increased risk of bleeding.
- Platelet count <100 x 10 9 /L)
- Purpuric rash with normal haemoglobin and white cell count

Question 2

What triggers ITP in children

Answer 2

Recent viral infection and follows an acute course, typically resolving within 6 months.

Question 3

What triggers ITP in adults

Answer 3

Primary ITP: criteria of ITP met without an underlying clear cause
Secondary ITP: antibody-mediated destruction can occur due to:
- SLE
- Chronic lymphoblastic leukaemia
- Drugs: penicillin, heparin, quinine
- Viruses: HIV, hepatitis C, VZV and CMV
- Pregnancy

Question 4

Epidemiology

Answer 4

Female
Age: adult ITP associated with advancing age
Co-morbid autoimmune diseases

Question 5

Signs

Answer 5

• Petechiae : <4mm bleed into the skin
• Purpura: 4-10mm bleed into the skin
• Ecchymosis: >10mm bleed into the skin
• Mucosal bleeding

Question 6

Symptoms

Answer 6

Bleeding does not typically present spontaneously unless the platelet count is <20 x 10 9 /L, however trauma or periods may be exacerbated at higher platelet counts.
Cutaneous bleeding has a preponderance for the lower limbs in ITP
Bruising
Epistaxis
Menorrhagia: heavy periods

Question 7

Diagnosis

Answer 7

ITP is considered a diagnosis of exclusion and so there are no specific investigations that can confirm the diagnosis/

Primary investigations:
- FBC: to ascertain low platelet count and screen for any underlying blood cancers
Peripheral blood smear: to assess platelet size and rule out clumping, which can give a falsely low platelet reading (pseudothrombocytopaenia)

Question 8

Treatment first line

Answer 8

No significant bleeding and mild thrombocytopaenia:
- Observation: to monitor for bleeding
- FIRST LINE = Corticosteroids: PREDNISOLONE
+/- Intravenous Immunoglobulin (IVIG): used as an adjunct to corticosteroids, or when steroids CI used in isolation.

Question 9

Presence of significant bleeding

Answer 9

Corticosteroids
Intravenous Immunoglobulin (IVIG): for rapid increase of platelet count in acute bleeding
Platelet transfusion: administration of 4-6 units of pooled platelets can increase the platelet count acutely. It does not correct the underlying abnormality and is thus reserved for emergencies where there is serious bleeding

Question 10

Second line

Answer 10

• Splenectomy: reserved for refractory cases not responding to medical management.
• Immunosuppressive agents: mycophenolate, rituximab or fostamatinib = alternative to splenectomy for those who have not responded to corticosteroids and other initial treatments