Thrombocytopenia: A Brief Overview

1
Thrombocytopenia A Brief Overview

• Corey Cudzilo, M-3
• 7/18/05

2
Platelets In General

• nL platelet count in adults ranges from
  150,000-450,000/microL
• Surgical bleeding usually does not occur until
  the platelet count is less than 50,000, and
  spontaneous bleeding does not occur until the
  platelet count is less than 10,000-20,000

3
Platelets In General

• Platelets are produced in bone marrow from
  Megakaryocytes
• An estimated 1000-5000 platelets are produced
  from each Megakaryocyte
• In normal adults platelet production is
  35,000-50,000/microL of whole blood per day.
  This value can be increased 8-fold during times
  of increased demand

www.UpToDate.com 2005
4
Mechanisms of Thrombocytopenia

• Decreased platelet production
• Increased platelet destruction
• Dilutional Thrombocytopenia
• Splenomegaly or splenic sequestration
• Pseudothrombocytopenia

5
Decreased Platelet Production

• Usually some offense that causes bone marrow
  suppression or damage
• Viral illness
• HIV (direct damage to Megakaryocytes)
• Chemo- or radiation therapy
• Congenital or acquired bone marrow aplasia or
  hypoplasia
• Direct EtOH toxicity
• Vit. B12 or Folate deficiency

6
Increased Platelet Destruction

• Idiopathic (Immune) Thrombocytopenic Purpura
• Alloimmune destructionPosttransfusion,
  Post-transplantation
• Disseminated Intravascular Coagulation
• Thrombotic Thrombocytopenic Purpura
• Antiphospholipid Antibody Syndrome
• Certain drugsHeparin, quinidine, valproate

7
Splenic Sequestration

• Normally, 1/3 of platelets are sequestered in
  the spleen in any given time
• In extreme splenomegaly, up to 90 of platelets
  can be trapped in the spleen
• Platelet size and life span is usually not
  affected
• Cirrhosis, Portal HTN, splenomegaly can all
  present with apparent thrombocytopenia, although
  these pts are not usually at risk for clinical
  bleeding

8
Clinical Presentation

• Asymptomatic
• Mucosal or cutaneous bleeding
• Petechiae
• Purpura
• Ecchymoses

www.UpToDate.com 2005
9
Common Presentations
10
Initial Approach

• HP
• Bleeding Hx
• Drug Ingestion
• CBC and peripheral smeargold standard
• Bone Marrow aspiration and biopsyindicated if no
  other etiology obvious unless pt is lt60yrs old.
  The presumptive Dx in that case is usually ITP.
• Idiopathic Thrombocytopenic Purpura (ITP) is a Dx
  of exclusion when HP,Drug ingestion,CBC, and
  peripheral smear do not suggest other etiologies

11
DDx of ITP
12
Treatments

• ObservationUsually appropriate if platelets are
  above 20,000/microL
• Glucocorticoids
• Platelet Transfusion
• In pts unresponsive to GCs, IV Ig will usually
  increase the platelet count to a safe level in
  1-3 days.

13
Sources

• Approach to the adult patient with
  thrombocytopenia. Steven A. Landlaw, MD/PhD.
  2005. UpToDate online.
• Evaluation and management of thrombocytopenia by
  primary care physicians. James George, MD. 2005.
  UpToDate online.