Difference between revisions of "Immune thrombocytopenic purpura"

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==Background==
 
==Background==
===GENERAL===
+
*Abbreviation: ITP
# low platelets and mucocutaneous bleeding
+
*Known as both "idiopathic" or "immune" thrombocytopenic purpura
# half occur in kids
+
*Acquired autoimmune disease resulting in destruction of platelets
# either primary or secondary to other disorder
+
*Because circulating platelets are functional, life-threatening bleeding only once platelet count <10K
# either acute or chronic > 6mo
+
*Chronically, the disease follows a course that is usually stable with intermittent and episodic flares, leading to clinically relevant thrombocytopenia<ref>Cines DB and Blanchette VS.  Immune Thrombocytopenic Purpura. New England Journal of Medicine.  Vol 346 (13); 995-1008.</ref>
# 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
 
  
===PATHOPHYS===
+
===Types===
# mediated by autoantibodies- platelets coated with igg antibodies undergo accelerated clearance in spleen and liver
+
{| {{table}}
# can get compensatory increase in platelet production in some pts
+
| align="center" style="background:#f0f0f0;"|'''Charateristic'''
# in other pts, get abnormal production destruction of intermedullary antibody coated platelets
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| align="center" style="background:#f0f0f0;"|'''Acute ITP'''
# level of thrombopoietin not increased
+
| align="center" style="background:#f0f0f0;"|'''Chronic ITP'''
# methods to tx are directed at 1- antibody prodctn, 2- platelet sensitization, 3- clearance, 4- production.
+
|-
 +
| Common age group||Younger children||Adults
 +
|-
 +
| Sex||Affects men/women equally||Usually women
 +
|-
 +
| Duration||Resolves in 1-2 months||Lasts > 3 months
 +
|-
 +
|Cause||Typically follows viral illness||More likely to have an underlying disease or autoimmune disorder (e.g. SLE)
 +
|-
 +
| Prognosis||||Rarely remits spontaneously or with treatment
 +
|}
  
===GENETICS===
+
==Clinical Features==
# can be seen in certain families and twins
+
*[[Petechiae]]
# HLA type may predict response to different tx's
+
*[[Epistaxis]]
# no consistent assoc btwn HLA types and ITP however
+
*[[Gingival bleeding]]
 +
*[[Vaginal Bleeding (Non-Pregnant)|Menorrhagia]]
 +
*[[GI bleeding]]
 +
*[[Intracranial hemorrhage]]
  
==Diagnosis==
+
==Differential Diagnosis==
# is dx of exclusion
+
{{Thrombocytopenia}}
#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
 
  
==Initial Management==
+
{{Purpura DDX}}
===ADULTS===
 
# 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.
 
  
===KIDS===
+
==Evaluation==
#outcome so good usually dont need to tx unless risk of intracranial hem- plts <10k- 20k
+
*Diagnosis of exclusion
# usually observe and avoid sports, ASA..
+
*Must differentiate acute ITP from chronic ITP, which suggests an underlying disorder
# if severe thrombocytopenia- can tx with IV IG or anti D IG. or prednisone.
+
*CBC shows normal cell lines except for the platelets (may have mild anemia)
  
Urgent Tx in Kids
+
==Management==
# neuro sxs, internal bleeding, surgery- tx with iv solumedrol and iv ig and platelet infusion
+
===Options===
# consider vincristine
+
*'''First choice in adults:''' Corticosteroids
# consider splenectomy
+
**[[Prednisone]] 60-100mg/d with taper after count reaches normal (50-75% remission rate by 3 wks)
# plasmapharesis not helpful
+
**[[Methylprednisolone]] 30mg/kg/d IV x 3 days (for life-threatening bleeding)
# consider antifibrinolytic/ aminocaproic acid fo mucosal bleeding
+
*'''First choice in children:''' Intravenous Immunoglobulin G ([[IVIG]]) 1gm/kg/d x 2 days
# for severe bleeding- iv ig and iv platelets
+
*High dose Anti-D ([[RhoGAM]]): patient must be Rh+ for it to work
 +
**Causes shift towards splenic destruction of antibody-coated Rh+ RBCs
 +
**Thereby has less functional capacity to destroy platelets
 +
**Dosage dependent on Hb level in mg/dL<ref>eMedicine. RhoGAM. http://reference.medscape.com/drug/rhogam-hyperrho-s-d-rho-d-immune-globulin-343143.</ref>
 +
***Hb>10, 250 IU/kg IV x1 over 5min
 +
***Hb<10, 125 IU/kg IV x1 over 5min
 +
*[[Platelet transfusion]]
 +
**Indicated for life-threatening bleeding  
 +
**Will ultimately be destroyed
 +
**Transfuse only following first dose of [[methylprednisolone]] or [[IVIG ]]
 +
***Holding transfusion until after first dose results in greater rise in platelet count
 +
***Calculate number of packs needed to increase count to over 50k (1 pack generally increases by 10k)
 +
*Estrogen for uterine bleeding: 25mg IV x1
  
==Management of First Relapse==
+
===Indications===
===ADULTS===
+
====Adults====
#no tx if asymptomatic with plt 30k
+
*Platelet >30K and asymptomatic: usually do not require treatment
# splenectomy if relapse or not response to steroids, iv ig or iv anti D ig
+
*Platelet count <30K: [[prednisone]]
 +
*Platelet <50K AND bleeding: [[prednisone]]
 +
*Life-threatening bleeding: IVIG, methylprednisolone, platelet transfusion
  
===KIDS===
+
====Children====
# delay splenectomy as long as possible- or if symptomatic > 1yr or severe thrombocytopenia
+
*Platelet count >30K: usually do not require treatment
 +
*Platelet count <20K + significant bleeding: IVIG
 +
*Platelet count <10K: IVIG
 +
*Life-threatening bleeding: IVIG, methylprednisolone, platelet transfusion
  
==SPLENECTOMY==
+
===Other Options===
# immunize against H flu, pneumoccus, and give daily prophylactic penicilin for 1 yr
+
*[[Splenectomy]] if above fails (only 2/3 effective)
 +
*[[Rho(D) Immune Globulin (RhoGAM)]]
 +
**Will induce mild hemolysis in Rh+ patients that decreases macrophage activity
 +
**Spleen will not destroy platelets covered in antibodies
 +
*[[Rituximab]]
 +
**May help as ITP is autoimmune process
  
==Chronic Refractory ITP==
+
==Disposition==
#30- 40% adults do not respond to splenectomy or have relapse p splenectomy
+
*'''Admit:''' platelet count <20K or significant mucous membrane bleeding
# hunt for accessory splene
+
*'''Discharge:''' platelet count >20K AND asymptomatic '''OR''' only minor petechiae
# 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.
 
 
 
===Children===
 
# azathioprine alone or in combination with cyclophosphamide.
 
  
 
==Complications==
 
==Complications==
# fatal bleeding from ICH- risk greatest in elderly or recurrent bleeding or no response to tx
+
*Rare: more common in elderly
 +
**[[Intracerebral bleeding]]
 +
**Severe [[GI bleeding]]
  
==Source ==
+
==See Also==
6/06 MISTRY
+
*[[ITP in Pregnancy]]
  
 +
==References==
 +
<references/>
 
[[Category:Heme/Onc]]
 
[[Category:Heme/Onc]]

Revision as of 14:49, 1 September 2019

Background

  • Abbreviation: ITP
  • Known as both "idiopathic" or "immune" thrombocytopenic purpura
  • Acquired autoimmune disease resulting in destruction of platelets
  • Because circulating platelets are functional, life-threatening bleeding only once platelet count <10K
  • Chronically, the disease follows a course that is usually stable with intermittent and episodic flares, leading to clinically relevant thrombocytopenia[1]

Types

Charateristic Acute ITP Chronic ITP
Common age group Younger children Adults
Sex Affects men/women equally Usually women
Duration Resolves in 1-2 months Lasts > 3 months
Cause Typically follows viral illness More likely to have an underlying disease or autoimmune disorder (e.g. SLE)
Prognosis Rarely remits spontaneously or with treatment

Clinical Features

Differential Diagnosis

Thrombocytopenia

Decreased production

Increased platelet destruction or use

Drug Induced

Comparison by Etiology

ITP TTP HUS HIT DIC
↓ PLT Yes Yes Yes Yes Yes
↑PT/INR No No No +/- Yes
MAHA No Yes Yes No Yes
↓ Fibrinogen No No No No Yes
Ok to give PLT Yes No No No Yes

Petechiae/Purpura (by cause)

Evaluation

  • Diagnosis of exclusion
  • Must differentiate acute ITP from chronic ITP, which suggests an underlying disorder
  • CBC shows normal cell lines except for the platelets (may have mild anemia)

Management

Options

  • First choice in adults: Corticosteroids
    • Prednisone 60-100mg/d with taper after count reaches normal (50-75% remission rate by 3 wks)
    • Methylprednisolone 30mg/kg/d IV x 3 days (for life-threatening bleeding)
  • First choice in children: Intravenous Immunoglobulin G (IVIG) 1gm/kg/d x 2 days
  • High dose Anti-D (RhoGAM): patient must be Rh+ for it to work
    • Causes shift towards splenic destruction of antibody-coated Rh+ RBCs
    • Thereby has less functional capacity to destroy platelets
    • Dosage dependent on Hb level in mg/dL[2]
      • Hb>10, 250 IU/kg IV x1 over 5min
      • Hb<10, 125 IU/kg IV x1 over 5min
  • Platelet transfusion
    • Indicated for life-threatening bleeding
    • Will ultimately be destroyed
    • Transfuse only following first dose of methylprednisolone or IVIG
      • Holding transfusion until after first dose results in greater rise in platelet count
      • Calculate number of packs needed to increase count to over 50k (1 pack generally increases by 10k)
  • Estrogen for uterine bleeding: 25mg IV x1

Indications

Adults

  • Platelet >30K and asymptomatic: usually do not require treatment
  • Platelet count <30K: prednisone
  • Platelet <50K AND bleeding: prednisone
  • Life-threatening bleeding: IVIG, methylprednisolone, platelet transfusion

Children

  • Platelet count >30K: usually do not require treatment
  • Platelet count <20K + significant bleeding: IVIG
  • Platelet count <10K: IVIG
  • Life-threatening bleeding: IVIG, methylprednisolone, platelet transfusion

Other Options

  • Splenectomy if above fails (only 2/3 effective)
  • Rho(D) Immune Globulin (RhoGAM)
    • Will induce mild hemolysis in Rh+ patients that decreases macrophage activity
    • Spleen will not destroy platelets covered in antibodies
  • Rituximab
    • May help as ITP is autoimmune process

Disposition

  • Admit: platelet count <20K or significant mucous membrane bleeding
  • Discharge: platelet count >20K AND asymptomatic OR only minor petechiae

Complications

See Also

References

  1. Cines DB and Blanchette VS. Immune Thrombocytopenic Purpura. New England Journal of Medicine. Vol 346 (13); 995-1008.
  2. eMedicine. RhoGAM. http://reference.medscape.com/drug/rhogam-hyperrho-s-d-rho-d-immune-globulin-343143.