Immune Thrombocytopenia (ITP) (BSH 2003, ash 2011, blood 2017)
Primary ITP: Acquired immune-mediated disorder characterized by a plt count <100 & absence of any obvious initiating or underlying disorder
It can be:
Persistent: 3-12 months
Chronic: >12 months
Adults – insidious onset, no clear cause, chronic process. 3 per 100,000 per year
Children – short lived, 2/3 recover in <6 months, 2/3 have a preceding infection
Secondary ITP: Hep C, HIV, Infection, SLE, MMR vaccine, Lymphoproliferative disorders
Thyroid disease: Hyper —> reduced survival, Hypo —> reduced production
Drugs: Antibiotics, Alcohol, Quinine, Environmental toxins
BM disorders: AA, MDS, MF, Leukaemia
H. pylori, FBC, Retic, Film, Immunoglobulins, G&S, DAT, HIV, Hep C
ANA: If positive predicts a chronic course in children
TSH + Thyroid antibodies: 10% of ITP patients develop hypothyroidism
When to consider BM biopsy
Prior to splenectomy
Tests Not Required
Antiplatelet antibodies: Glycoprotein-specific antibodies – not specific
Antiphospholipid antibodies: Positive in 40% but does not predict response to treatment
1st Line: Steroids, IVIg, Anti-D
2nd Line: Rituximab, Splenectomy, TPO agonists, Steroid-sparing immunosuppressants
Beyond 2nd Line: TPO agonists or toxic treatments (Campath, HSCT, Chemotherapy)
Management of Adult ITP
Tailored to patient, no fixed protocol
Haemorrhagic death is rare – 0.01 cases / adult patient / year
1.5-1.8% risk of intracranial haemorrhage
Treatment very rarely required if platelet count >50, or even >30
There are no head-to-head trials to enable recommendation of one Rx over another.
But note TPO agonists have gone through proper RCT’s unlike older therapies
Tranexamic Acid, Mirena coil / OCP
Patient support groups
Pred 0.5-2mg/kg/day until response, then taper and stop by 4 weeks
Dex 40mg/day for four days and stop
Methylpred if oral route not an option
Dose: 1g/kg as a single infusion
Quicker time to response than steroids.
50-75 micrograms/kg as a single dose
Suitable for Rh D+, non-splenectomised patients
Thought to work by coating Rh D+ cells leading to their preferential destruction by the spleen, sparing the platelets.
SE: DIC, Renal failure, Intravascular haemolysis
80% respond, 66% for >5 years. Unmatched by other therapies
10% complication rate with laparoscopic approach. Aim plt >20 prior to surgery.
Hib/Men C, Polyvalent Pneumococcal, Men B, Men ACWY, Annual ‘flu
40% respond, 20% for 3-5 years
375mg/m2 weekly for four weeks. May be more effective combined with dex
Given to >1 million patients worldwide with good tolerability
60-90% response rate but requires maintenance therapy. 1-2 weeks to first effect
Romiplostim: 1-10 microg/kg SC weekly
Eltrombopag: 25-75mg PO daily. 2 hours apart from food, 4 hours from calcium-foods
SE: small number of reports of increased marrow reticulin.
Recommended as a treatment for adults with chronic ITP only if:
Condition is refractory to standard and rescue therapies, and
There is severe disease with high bleeding risk that requires frequent treatment.
Management of Childhood ITP
Remember diagnosis of exclusion, continue to re-visit over time
After 3-6 months consider:
BMAT, Immunoglobulins, ANA, APL Ab, HIV, H. pylori, Hep C
97% clinically asymptomatic
If bleeding, grade severity 1-4. Treat if grade 3 or 4.
Watch and Wait management should still be consented for
Avoid contact sports, continue all other activities
To raise plt count
IVIg – rapid rise in >80% of patients
IV Anti-D – Small dose, gives transient rise
Platelet transfusion with IV Steroids + IVIg
As per adults. No TPO studies in children yet.