Thrombocytopenia

Question 1

What are platelets (thrombocytes)

Answer 1

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

Question 2

What is the normal range for platelets?

Answer 2

150,000 to 300,000/mm3

Question 3

What are the causes of Thrombocytopenia? (MINI)

Answer 3

Metabolic
Infectious
Neoplastic
ITP

Question 4

Metabolic causes of thrombocytopenia?

Answer 4

Drugs Particularly Heparin, Penicillins, Sulfas, Anticonvulsants and Quinine
Thrombotic Thrombocytopenic Purpura / Hemolytic Uremic Syndrome
Severe Bleeding or Hypersplenism

Question 5

Infectious causes of thrombocytopenia?

Answer 5

Particularly HIV and Other Viral Infections

Sepsis +/- Disseminated Intravascular Coagulation (DIC)

Question 6

Neoplastic causes of thrombocytopenia? (2)

Answer 6

DIC

Myelophthisis

Question 7

Heparin Induced Thrombocytopenia (HIT)

Answer 7

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

Question 8

What needs to be done if HIT is present?

Answer 8

stop the heparin

Question 9

What are 4 common drugs that cause thrombocytopenia?

Answer 9

Penicillins and Their Cousins Cephalosporins
Sulfa Drugs
Anticonvulsants
Quinine Containing Drugs or Beverages

Question 10

Thrombocytopenia is created by what?

Answer 10

created by Microthrombi forming in Small Vessels Consuming Platelets and Inducing a Microangiopathic Hemolytic Anemia

Question 11

what are 5 things that could be found on physical exam for thrombocytopenia?

Answer 11

Fluctuating Neurological Sx
Abnormal speech
Confusion
Jaundice
Purpura/Petechiae

Question 12

The classic Pentad

Thrombotic Thrombocytopenic Purpura (TTP) & Hemolytic Uremic Syndrome (HUS)

Answer 12

Microangiopathic Hemolytic Anemia, T.penia, Renal Failure, Fluctuating Neurologic Signs and Sx & Fever

Question 13

Who is hemolytic uremic syndrome more common in?

Answer 13

children

Question 14

The Laboratory Diagnosis of TTP is Established By:

Answer 14

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

Question 15

Treatment of TTP & HUS is Urgent Plasmapharesis

Answer 15

If a potential Offending Agent Can be Identified, it should be Withdrawn
Steroids are Also Prescribed and are of Some Benefit

Question 16

Epidemiology of Thrombotic Thrombocytopenic Purpura (TTP) & Hemolytic Uremic Syndrome (HUS)

Answer 16

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

Question 17

Infectious Etiologies of Thrombocytopenia

Answer 17

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)

Question 18

Disseminated Intravascular Coagulation (DIC)

Answer 18

A Syndrome Not a Disease

a serious disorder in which the proteins that control blood clotting become over active

Question 19

DIC have 3 distinguishing labs

Answer 19

Platelets are decreased
Soluble Clotting Factors are decreased
PT, a PTT & Fibrin Split Products are increased

Question 20

Myelophthisis anemia

Answer 20

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

Question 21

Immune Thrombocytopenic Purpura (ITP)

Answer 21

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

Question 22

Epidemiology of ITP?

Answer 22

~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

Question 23

What happens with Platelet Counts from 20,000 –

100, 000

Answer 23

May be Asymptomatic & Discovered Fortuitously

May Be Associated with Easy Bruising or Heavy Menses

Question 24

What happens with Platelet Counts less than 5,000

Answer 24

Intracranial hemorrhages
GI bleeding
Spontaneous Organ Bleeding

Question 25

What happens with Platelet Counts from 5000 - 20,000

Answer 25

Spontaneous bruises (purpura or petechiae) and hematoma formation
Mucocutaneous bleeding

Question 26

What is a grave sign of ITP that requires urgent intervention?

Answer 26

Wet Purpura” are a Grave Sign that Requires Urgent Intervention
High Dose Steroids
Intravenous Immunoglobulin & Platelet Transfusion may be Needed

Question 27

What are 5 clinical findings that may require more urgent/ aggressive treatment?

Answer 27

Fever
Malnutrition
Advanced Age
Extensive Comorbidities
Inability to Cooperate with Outpatient Therapy

Question 28

Children usually present with an Acute Thrombocytopenia when?

Answer 28

Usually follows a Viral Infection

Usually Resolves within 6months

Question 29

What is the only lab value that may not be normal with ITP?

Answer 29

Peripheral Smear Normal Except Sometimes with Giant Platelets and Associate Low Platelet Count

Question 30

What is the mainstay treatment of ITP

Answer 30

Steroids, short course, until platelet counts improve, taper to off

Question 31

What is the second line treatment of ITP

Answer 31

IVIG
Rituximab (anti CD 20)
Anti Rh-D (anti Rh + RBCs  Hemolysis and RE Blockade)
Thrombopoietin receptor agonists

Question 32

What is last resort treatment of ITP?

Answer 32

splenectomy