Immune thrombocytopaenic purpura (ITP)

D69.3

DESCRIPTION

A common bleeding disorder of childhood due to the autoimmune destruction of platelets.

It occurs most frequently in children aged 2 to 5 years and often follows infection with viruses including HIV and medications. Chronic ITP (more than 6 months duration) occurs in 10 to 20% of children with ITP.

Complications include severe haemorrhage and bleeding into vital organs.

DIAGNOSTIC CRITERIA

Clinical

  • Sudden onset of bruising and bleeding, either spontaneously or after minor trauma, into the skin and mucous membranes and rarely into the organs in an otherwise well child.
  • The lesions may range from pinpoint petechial bleedings to large ecchymoses, and are often increased on pressure points.
  • Epistaxis is common.
  • Exclude child abuse.
  • The presence of the following makes the diagnosis of ITP unlikely:
    • splenomegaly,
    • masses,
    • hepatomegaly,
    • joint swelling,
    • lymphadenopathy,
    • bone pain,
    • rashes present other than petechiae or ecchymoses.

Investigations

  • Thrombocytopaenia with normal white cell count and differential, and normal haemoglobin and red cell morphology, other than the effects of blood loss. Mean Platelet volume is often increased.
  • Normal INR (PT) and partial thromboplastin time (PTT).
  • Abundant megakaryocytes on bone marrow aspiration with normal erythroid and myeloid cellularity.
  • A normal LDH and uric acid help to rule out leukaemia.
  • Indications for bone marrow biopsy/aspiration: Prior to starting steroids, or any other abnormality on FBC or any atypical cells on differential count.
  • Test all newly diagnosed cases for HIV.

Follow up patients with diagnosis of ITP not confirmed with bone marrow aspiration for development of new clinical signs and abnormalities on laboratory investigations.

GENERAL AND SUPPORTIVE MEASURES

  • Avoid:
    • platelet transfusions unless bleeds are life-threatening,
    • contact sport, injury and trauma, and
    • dental procedures in acute phase.
  • Re-assure patient and family that resolution usually occurs.

MEDICINE TREATMENT

Avoid medication that affects platelet function, e.g. NSAIDs and aspirin.

Acute ITP

Active bleeding:

  • Prednisone, oral, 4 mg/kg/dose as a single daily dose for 4 days.
    • Stop after 4 days without tapering dose.

Chronic ITP

Intermittent treatment if platelets ≤ 10 x 10⁹/L and significant bleeding episodes:

  • Prednisone, oral, 4 mg/kg/dose as a single daily dose for 4 days.
    • Stop after 4 days without tapering dose.

Acute life-threatening bleeds (e.g. intracranial bleeding): (acute or chronic ITP)

  • Methylprednisolone, IV, 30 mg/kg/dose administered over 30–60 minutes as a single daily dose for 3 days.
    • Maximum dose: 1 g.
    • Beware of arrhythmias, hypertension, etc.
    • Check BP daily.

AND

After administration of methylprednisolone:

  • Paediatric platelets concentrate, leuco-depleted 5-10mL/kg

Refer to specialist for advice on further management.

SURGICAL TREATMENT

Consider splenectomy in children 5 years and older with chronic ITP for more than one year plus significant bleeding or substantial limitation in activities as a result of the ITP.

Pre-splenectomy

  • 2 weeks prior to surgery:
    • PCV13, IMI, 0.5 mL, followed by PPV23, IMI, 0.5 mL 8 weeks later.
    • HIB booster, IMI 0.5 mL.
    • Meningococcal vaccine, IMI, 0.5 mL.

Post splenectomy

  • Phenoxymethylpenicillin, oral, 12 hourly.
    • If < 5 years of age: 125 mg.
    • If > 5 years of age: 250 mg.
    • Give indefinitely until at least until 18 years.
  • Pneumococcal polysaccharide vaccine. Repeat vaccination as a booster 5 years after the initial dose.
  • Annual influenza vaccine.
  • Hib and MCV boosters every 5-10 years
  • Catch up conjugate pneumococcal vaccine:
    • If < 12 months of age: 3 dose series.
    • 12 months of age and older: 2 doses 8 weeks apart.

REFERRAL

  • Suspected ITP with unusual features such as splenomegaly or lymphadenopathy.
  • ITP complicated by severe haemorrhage, bleeding into vital organs or an intracranial haemorrhage.
  • ITP needing surgery.
  • ITP that fails to resolve in 6–12 months on adequate treatment (chronic ITP).
  • If there is no local capacity to fully investigate the condition.