Immune thrombocytopenic purpura
- low platelets and mucocutaneous bleeding
- half occur in kids
- either primary or secondary to other disorder
- either acute or chronic > 6mo
- usually presents days to weeks after infection
- in kids, 70% resolve in 6 mo regardless of tx or not
- adults usually chronic, insidous onset and more likely in women than men
- mediated by autoantibodies- platelets coated with igg antibodies undergo accelerated clearance in spleen and liver
- can get compensatory increase in platelet production in some pts
- in other pts, get abnormal production destruction of intermedullary antibody coated platelets
- level of thrombopoietin not increased
- methods to tx are directed at 1- antibody prodctn, 2- platelet sensitization, 3- clearance, 4- production.
- can be seen in certain families and twins
- HLA type may predict response to different tx's
- no consistent assoc btwn HLA types and ITP however
- is dx of exclusion
- can get secondary ITP in SLE, antiphospholid syn, immune deficiency states, leukemia, lymphoma, HIV, Hep C, heparin and quinidine.
- duration of bleeding tells acute from chronic
- absence of systemic symptoms helps rule out secondary forms and other dxs
- family hx usually negative.
- physical exam shows platelet type bleeding-petechia, purpura, conj hem,
- if spleen very big, consider other dx
- can see anemia if have lots of blood loss
- can see large young plateltets on perif smear
- bone marrow bx- debatetable- but need it if atypical case, fever, pain, neutropenia, unexplained macrocytosis.
- dx by measuring platelet assoc antibodies- fair sensitivity, specificity and predictive value
- neg test does not rule it out
- if plts above 50k- will dx incidentally
- plts 30k- 50k- will get easy bruising
- petechia and purpura at 1-k- 30k
- <10k at risk for internal bleeding
- adults usually require tx with prednsone at tme of presentation
- can also use Anti- D immune globulin in Rh + pt
- IV IG used for internal bleeding
- splenectomy within 3- 6mo if more than 10- 20 mg prednisone per day.
- outcome so good usually dont need to tx unless risk of intracranial hem- plts <10k- 20k
- usually observe and avoid sports, ASA..
- if severe thrombocytopenia- can tx with IV IG or anti D IG. or prednisone.
Urgent Tx in Kids
- neuro sxs, internal bleeding, surgery- tx with iv solumedrol and iv ig and platelet infusion
- consider vincristine
- consider splenectomy
- plasmapharesis not helpful
- consider antifibrinolytic/ aminocaproic acid fo mucosal bleeding
- for severe bleeding- iv ig and iv platelets
Management of First Relapse
- no tx if asymptomatic with plt 30k
- splenectomy if relapse or not response to steroids, iv ig or iv anti D ig
- delay splenectomy as long as possible- or if symptomatic > 1yr or severe thrombocytopenia
- immunize against H flu, pneumoccus, and give daily prophylactic penicilin for 1 yr
Chronic Refractory ITP
- 30- 40% adults do not respond to splenectomy or have relapse p splenectomy
- hunt for accessory splene
- tx with prednisone, iv ig
- next step is medicine that impedes platelet clearance- Danazol, Dapsone, vinca alkaloids.
- if splenectomized, do not give ig anti D ig.
- immunesuppression if platelet <20k and no response to above tx- use azathioprine or cyclophosphamide
- Azathioprine watch LFT's- is also carcinogenic
- Cyclophoshamide- marrow suppression, hem cystitis, bladder fibrosis, alopecia, infertility, leukemia and teratogenic.
- azathioprine alone or in combination with cyclophosphamide.
- fatal bleeding from ICH- risk greatest in elderly or recurrent bleeding or no response to tx