Thrombocytopenia Flashcards
What are platelets (thrombocytes)
Small, disk shaped, cell fragments without a nucleus
Produced in the bone marrow
Derived from the precursor Megakaryocytes
Average Lifespan in Peripheral Blood Under Normal Circumstances 7 days
Involved in blood clotting (hemostasis)
Reserve platelets are stored in the spleen, and released when needed
Old platelets are destroyed in the spleen
What is the normal range for platelets?
150,000 to 300,000/mm3
What are the causes of Thrombocytopenia? (MINI)
Metabolic
Infectious
Neoplastic
ITP
Metabolic causes of thrombocytopenia?
Drugs Particularly Heparin, Penicillins, Sulfas, Anticonvulsants and Quinine
Thrombotic Thrombocytopenic Purpura / Hemolytic Uremic Syndrome
Severe Bleeding or Hypersplenism
Infectious causes of thrombocytopenia?
Particularly HIV and Other Viral Infections
Sepsis +/- Disseminated Intravascular Coagulation (DIC)
Neoplastic causes of thrombocytopenia? (2)
DIC
Myelophthisis
Heparin Induced Thrombocytopenia (HIT)
If HIT occur it is usually after D# 5 of Treatment or at Re-exposure.
Platelets are Usually ~ 25,000 – 75,000 range
Bleeding is Rare
Diagnosed by Ordering a Test for Heparin Induced Anti-platelet Antibodies
What needs to be done if HIT is present?
stop the heparin
What are 4 common drugs that cause thrombocytopenia?
Penicillins and Their Cousins Cephalosporins
Sulfa Drugs
Anticonvulsants
Quinine Containing Drugs or Beverages
Thrombocytopenia is created by what?
created by Microthrombi forming in Small Vessels Consuming Platelets and Inducing a Microangiopathic Hemolytic Anemia
what are 5 things that could be found on physical exam for thrombocytopenia?
Fluctuating Neurological Sx Abnormal speech Confusion Jaundice Purpura/Petechiae
The classic Pentad
Thrombotic Thrombocytopenic Purpura (TTP) & Hemolytic Uremic Syndrome (HUS)
Microangiopathic Hemolytic Anemia, T.penia, Renal Failure, Fluctuating Neurologic Signs and Sx & Fever
Who is hemolytic uremic syndrome more common in?
children
The Laboratory Diagnosis of TTP is Established By:
Microangiopathic Hemolytic Anemia with Thrombocytopenia
Normal Clotting Studies, e.g. PT, aPTT
increased LDH, increased Indirect Bilirubin,
decreased Haptoglobin,
increased Retics with a Negative Direct Coombs
Treatment of TTP & HUS is Urgent Plasmapharesis
If a potential Offending Agent Can be Identified, it should be Withdrawn
Steroids are Also Prescribed and are of Some Benefit
Epidemiology of Thrombotic Thrombocytopenic Purpura (TTP) & Hemolytic Uremic Syndrome (HUS)
Mortality Today with Prompt Diagnosis and Treatment Should Be < 30%.
If Renal Failure Predominates, Dialysis May Be Needed
Long term Steroid Use May Be Needed to Help Prevent Relapse
Relapses Occur in 15 – 45% of Cases
Infectious Etiologies of Thrombocytopenia
Viral Infections Such as Mononucleosis Cause Thrombocytopenia
The Mechanism is Usually Immune
Treatment is Supportive or Sometimes Steroids
HIV associated Thrombocytopenia Should Be Treated with HAART ( Highly Active Anti-Retroviral Therapy)
Disseminated Intravascular Coagulation (DIC)
A Syndrome Not a Disease
a serious disorder in which the proteins that control blood clotting become over active
DIC have 3 distinguishing labs
Platelets are decreased
Soluble Clotting Factors are decreased
PT, a PTT & Fibrin Split Products are increased
Myelophthisis anemia
form of bone marrow failure that results from the destruction of bone marrow precursor cells and their stroma, which nurture these cells to maturation and differentiation
Immune Thrombocytopenic Purpura (ITP)
ITP is an Autoimmune Condition with Antibodies Directed against Several Platelet Associated Surface Antigens
The Abs that Bind to Platelets Leads to Platelet Destruction Primarily in the Spleen
Epidemiology of ITP?
~15 new cases/105 population / year
children accounting for half of the new cases each year
Childhood cases are usually Self Limit
Adult Cases Tend to be Chronic
The Male to Female ratio is about 1:1
Median Age of Childhood cases 2 - 6 y.o
The Median Age of Adult Cases is ~ 40 y.o
What happens with Platelet Counts from 20,000 –
100, 000
May be Asymptomatic & Discovered Fortuitously
May Be Associated with Easy Bruising or Heavy Menses
What happens with Platelet Counts less than 5,000
Intracranial hemorrhages
GI bleeding
Spontaneous Organ Bleeding
What happens with Platelet Counts from 5000 - 20,000
Spontaneous bruises (purpura or petechiae) and hematoma formation Mucocutaneous bleeding
What is a grave sign of ITP that requires urgent intervention?
Wet Purpura” are a Grave Sign that Requires Urgent Intervention
High Dose Steroids
Intravenous Immunoglobulin & Platelet Transfusion may be Needed
What are 5 clinical findings that may require more urgent/ aggressive treatment?
Fever Malnutrition Advanced Age Extensive Comorbidities Inability to Cooperate with Outpatient Therapy
Children usually present with an Acute Thrombocytopenia when?
Usually follows a Viral Infection
Usually Resolves within 6months
What is the only lab value that may not be normal with ITP?
Peripheral Smear Normal Except Sometimes with Giant Platelets and Associate Low Platelet Count
What is the mainstay treatment of ITP
Steroids, short course, until platelet counts improve, taper to off
What is the second line treatment of ITP
IVIG
Rituximab (anti CD 20)
Anti Rh-D (anti Rh + RBCs Hemolysis and RE Blockade)
Thrombopoietin receptor agonists
What is last resort treatment of ITP?
splenectomy
