Immune Thrombocytopenic Purpura

So, I finished my surgery placement- at long last! It’s not that I hated it, I just didn’t love it that much. The waking up early, the not feeling part of the team because all the patients are scattered and you don’t see the consultants very much. And theatre can be very boring if you’re just watching. Although, I did sort of enjoy the times I scrubbed in and helped out- 4 times, which is actually more than most of the other students I’ve spoken to.

Lessons from surgery: I do not want to be a surgeon– I think that’s enough of a lesson.

A bit about hernias

So, moving on to better things- I’ve started a haematology placement. It already feels more student-friendly than surgery. The consultant spent a good 5-10 minutes going through how his team works and what he expects from us- which was a bit disconcerting as he seems to be keen on attendance- but also quite reassuring because it means he does actually want medical students to be a part of his team.

Today, we had an induction day and we were just meant to meet our team but something got lost in translation and we may not have stressed that ‘we just wanted to introduce ourselves’ enough and so we ended up in General Haematology Clinic, which was a whole lot of anaemia and a whole lot of ITP.


Immune Thrombocytopenic Purpura (ITP)

Definition: syndrome characterised by immune destruction of platelets resulting in bruising or bleeding tendency

Aetiology/ risk factors:

-often idiopathic

-Acute ITP usually seen after viral infection in children, 2 weeks after infection

-Chronic ITP more common in adults

May be associated with:

-Infections: HIV, EBV, malaria

-Autoimmune disease: SLE, thyroid disease

-Malignancies

-Drugs: e.g. quinine

Autoantibodies that bind to platelet membrane proteins result in thrombocytopenia (low platelet count)

Epidemiology:

-Acute ITP presents in children 2-7 years old

-Chronic ITP presents in adults- 4x more common in women

Symptoms:

-Easy bruising

-Mucosal bleeding

-Menorrhagia (heavy periods)

-Epistaxis (nose bleeds)

Signs:

-Visible petechiae (small red or purple spot on the skin, caused by a minor bleed from broken capillary blood vessels)

Image result for immune thrombocytopenic purpura

-Bruises (purpura or ecchymoses)- especially dependent pressure areas

-No splenomegaly

Investigations:

Diagnosis is of exclusion.

Want to exclude myelodysplasia, acute leukaemia, marrow infiltration.

-FBC: low platelets (normal value = 150-400 x109/L

Clotting screen: normal PT/APPT/ fibrinogen (not a problem with coagulation)

-Autoantibodies: antiplatelet antibody may be present but not used routinely for diagnosis. Also, anticardiolipin antibody and antinuclear antibody.

Blood film: rule out pseudothrombocytopenia caused by platelet clumping, which gives falsely low platelet counts

Bone marrow: exclude other pathology. Normal or elevated megakaryocytes (platelet precursor)

Management:

-no treatment if mild

oral corticosteroids (1st line)

Give prednisolone (1mg/kg/d) if symptomatic or platelets < 20 x109/L, and reduce after remission. Aim to keep platelets > 30 x 109/L (takes a few days to work).

Splenectomy– has a ≤ 80% cure rate- perform if relapsing

Immunosuppressants in refractory cases- e.g. azathioprine, mycophenolate, cyclophosphamide- if splenectomy not curative

IV infusion of immunoglobulin– IVIG- may temporarily raise platelet count.

-Platelet transfusions usually contraindicated unless severe bleeding or during splenectomy, as these are quickly destroyed by the autoantibodies.

-There are some newer agents available that can be tried e.g. Eltrombopag–  an oral thrombopoietin- receptor agonist that stimulates platelet production

Complications:

-mucosal bleeding

-major haemorrhage is rare

Prognosis:

-usually sudden self-limiting purpura in children, with platelets recovering within 1-2 months

-less likely to resolve spontaneously in adults but can be controlled medically in 60-90% of cases

References: Cheese & Onion, Rapid Medicine
Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s