ITP – Idiopathic Thrombocytopaenic Purpura

A 4-year-old girl presents with bruising over her legs, trunk and face.  Mum has noticed them appear over the last week.  She has been completely well with no other symptoms.  There is no history of trauma.  After an anxious 1 hour wait, the bloods are back.

Hb 113, WCC 7.3, Plt 8 x 10⁹/L.

Bottom Line

Uncomplicated idiopathic thrombocytopenic purpura (ITP) is new-onset bruising and bleeding with a platelet count <100 x 10⁹/L in the absence of other symptoms.

It generally resolves itself in 80% by six months.

5% will have a recurrence

Only treat if there is active bleeding, not just because of a low platelet count.

Advise parents to avoid NSAIDS and lookout for signs of bleeding.

Follow up regularly for the first six weeks or until platelet count stabilizes.

What is ITP?

Idiopathic thrombocytopenic purpura (ITP) is a reduction in platelet count without any other cause (<100 × 10⁹/L).  While normal platelets last eight to ten days, autoantibodies destroy them in the first few hours in ITP. It has a peak incidence of two to five years of age (chronic ITP peaks in adolescence). 

There is often a recent history (one to six weeks) of a viral illness or immunization.

What are the common symptoms and signs of ITP?

The most common sign is petechiae (1-5 mm red or purple non-blanching spots) on the skin or mucosa – these indicate capillary haemorrhages.  Some mucocutaneous bleeding is often seen, but it is rare for this to be severe (<5%).

Other symptoms of autoimmune disorders should NOT be present in ITP – e.g. no weight loss, rashes, alopecia, joint swelling. The examination should be normal with no hepatosplenomegaly or lymphadenopathy.

How is it diagnosed?

It is diagnosed by having a low platelet count with normal haemoglobin (unlike in leukaemia, TTP, HUS, and DIC). If there is a history of previous bleeding, consider other diagnoses. Bone marrow aspirate is only recommended if there is persistent bleeding in spite of a platelet count >20 × 10⁹/L.

What treatment should we use?

The answer is simple: treat the patient not the platelet count.  Assess if the patient has haematuria, melaena, menorrhagia, epistaxis, mucosal bleeding or tonsillar purpura/petechiae.

Although there is variation between specialists, they will all be more concerned with the signs of wet purpura or haematuria rather than just the petechiae on the skin.

Steroids

Prednisolone 1-2mg/kg OD for at least three weeks, then taper
OR
Methylprednisolone 30mg/kg/day for three days, then 20mg/kg /day for four days

IVIG (intravenous immunoglobulin)

Consider where there is significant bleeding (0.8-1g/kg) – it can rapidly raise the platelet count. Effects takes place in one to five days and lasts for two to four weeks.

Platelets

Only give platelets if there is an intracranial haemorrhage (ICG) or significant bleeding.  They can be effective after IVIG administration, and this can prolong platelet survival (otherwise, transfused platelets are quickly destroyed)

When to admit?

Admit if there is significant bleeding: epistaxis>1 hour; haematemesis; haemoptysis, intracranial haemorrhage, melaena.  Or if there is an unclear diagnosis or problematic social circumstances.

When will it go away?

Most ITP self-resolves.  80% will have resolved by six months (with or without treatment).  5% of ITP patients will have a recurrence. Although it seems counterintuitive, the lower the platelet count at the beginning, the better.  Uncomplicated ITP normally has a platelet count of <20 × 10⁹/L. Chronic ITP does not resolve within six months and accounts for 10% of ITP.

Could it be anything else?

Confirmation is based on excluding other differentials, such as acute leukaemia, aplastic anaemia, and HUS. A full blood count and film are usually adequate to make the diagnosis.

What do you need to tell the parents to look out for?

While the platelets are low, the patient is at risk of bleeding.  ICH is a serious but rare (1%) side effect.  Parents should watch out for any signs of ICH, urinary bleeding, GI bleeding, excessive mucosal bleeding and menorrhagia (in older patients).

They should avoid NSAIDs while the platelet count is low.

Older children should avoid contact sports.  This is completely impractical for young children so is not helpful advice – will only stress out the parents!

When to follow up?

Patients should be reviewed within two weeks of initial presentation and have a repeat FBC. Initially, aim for weekly GP follow-up and then PRN until resolution.

Paediatric outpatient review at six weeks, three months, and six months. Refer to haematology if unclear diagnosis, unresolved after six months or a haematological malignancy is suggested by the blood count.

Selected references

Pediatric EM Morsels – Wet purpura and ITP

UMEM Educational Pearls – ITP

Royal Children’s Hospital, Melbourne – Guidelines for ITP

Princess Margaret Hospital for Children – ITP Guideline

BMJ BestPractice – ITP

Grainger JD, Rees, JL, Reeves M, Bolton-Maggs PHB.  Changing trends in the UK management of childhood ITP. Arch. Dis. Child. 2012;97:8-11.[/toggle]