Immune thrombocytopenic purpura

This page is for adult patients. For pediatric patients, see: Immune thrombocytopenic purpura (peds).

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

ITP 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

• Petechiae
• Epistaxis
• Gingival bleeding
• Menorrhagia
• GI bleeding
• Intracranial hemorrhage

Differential Diagnosis

Thrombocytopenia

Decreased production

• Marrow infiltration (tumor or infection)
• Viral infections (rubella, HIV)
• Marrow suppression (commonly chemotherapy or radiation)
• Congenital thrombocytopenia
  • Fanconi anemia
  • Alport syndrome
  • Bernand Soulier
• Vitamin B12 and/or folate deficiency

Increased platelet destruction or use

• Idiopathic thrombocytopenic purpura
• Thrombotic Thrombocytopenic Purpura (TTP)
• Hemolytic Uremic Syndrome (HUS)
• Disseminated Intravascular Coagulation (DIC)
• Viral infections (HIV, mumps, varicella, EBV)
• Drugs (heparin, protamine)
• Postransfusion or Posttransplantation
• Autoimmune destruction (SLE or Sarcoidosis)
• Mechanical destruction
  • Artificial valves
  • ECMO
• HELLP syndrome
• Excessive hemorrhage
• Hemodialysis, extracorporeal circulation
• Splenic Sequestration
  • Occurs in Sickle cell disease and Cirrhosis

Drug Induced

• sulfa antibiotics, ETOH, ASA, thiazide diuretics/furosemide

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)

• Abnormal platelet count and/or coagulation
  • Septicemia
  • Idiopathic thrombocytopenic purpura (ITP)
  • Hemolytic uremic syndrome
  • Leukemia
  • Coagulopathies (e.g. hemophilia)
  • Henoch-Schonlein Purpura (HSP)
  • Acute hemorrhagic edema of infancy (AHEI)
• Hypersensitivity vasculitis
• Primary vasculitides
  • Wegener's
  • Microscopic polyangiitis
  • Eosinophilic granulomatosis with polyangiitis (Churg-Strauss syndrome)
• Secondary vasculitides
  • Henoch-Schonlein purpura
  • Connective tissue disorder
    • Systemic lupus erythematosus
  • Scurvy
  • Infectious disease
    • Hepatitis B
    • Hepatitis C
• Trauma

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
    • 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

• Rare: more common in elderly
  • Intracerebral bleeding
  • Severe GI bleeding

See Also

• ITP in Pregnancy
• TTP