1. Thrombocytopenia
An overview
PRESENTED BY: ALAA HABBAL

2. Outline
 Platelets production review
 Define thrombocytopenia
 Pathophysiology
 Causes
 Thrombocytopenia in pregnancy.
 Thrombocytopenia in neonates
 When to worry about bleeding
 When to worry about thrombosis
 Evaluation of thrombocytopenia
 Glance at platelets collection & transfusion.

3. Platelets
are
produced in the
bone marrow
from
megakaryocytes
(1000-5000 plts)
35,000 to 50,000
plts/ µL of blood
production
can be
increased
up to
eightfold
One third of
platelets are
sequestered
in spleen
Platelets life
span is 5 -9 days
Normal platelet
count:
150,000 -
450,000 µL.

4. What is a low platelet count
(Thrombocytopenia)
 platelet count below the lower limit of
normal <150,000/microL [150 x 109/L] for adult.
 Degrees of thrombocytopenia can be further subdivided into:
o mild (platelet count 100,000 to 150,000/microL),
o moderate (50,000 to 99,000/microL), and
o severe (<50,000/microL) greater risk of bleeding but not absolute.

5. CONT…
 variation of the platelet count in a given individual is limited.
 A small proportion of the population (approximately 2.5 percent) will
have a baseline platelet count lower than 150,000/microL.
 50 percent reduction in platelet count, but count is still >150,000/microL
may be a clinical significant.

6. - decreased
platelet
production in the
bone marrow
- peripheral
platelet
destruction by
antibodies or
- consumption
in thrombi
- dilution from
fluid
resuscitation or
- massive
transfusion
- sequestration
of platelets in
the spleen
(splenomegaly)
Thrombocytopenia
pathophysiology

7. Causes of
Thrombocytopenia
Disorder of
production
Ineffective
production
Decrease in
Megakaryocytes
Congenital
Disorder
Fanconi,s
anemia
Acquired Disorders
Radiation, Alcohol
Thiazide diuretics,
Chloramphenicol,
Cancer
chemotherapy
Marrow replacement
by Malignant Cell
Metastatic carcinoma
Leukemia, lymphoma,
myeloma
Myelofibrosis
• Vitamin B12 or folate
deficiency .
• Di Guglielmo’s syndrome
(erythroleukemia)
Distribution &
Dilution
Splenomegaly or
hypersplenism
Hypothermia; transfusion
Disorder of
Destruction
Isolated
consumption
Combined
consumption
Immune
Destruction
DIC & its causes
Obstetric complication
Neoplasms (promylelocytic
leukemia)
Bacterial and viral infections
TTP-HUS
Drug induced
Quinidine,
heparin
ITP

8. Disseminated intravascular coagulation (DIC)
Pathophysiology
● Hyper-activated
coagulation system.
● Hyper-activated fibrin-lytic
system, or both
simultaneously.
●Coagulation factors and
plts consumed as soon as
they are made.
● Secondary to an
underlying disease or
condition. Ex; sepsis,
placenta abruption, snake
bites, toxin, trauma, graft vs.
host disease, and burns.
Clinical Finding
● Patients are at risk of
bleeding and thrombosis.
Laboratory Finding
•Thrombocytopenia
•Prolonged PT, APTT,
thrombin time.
•Decreased fibrinogen.
•Elevated D-dimers.
•Schistocytes on the
peripheral blood smear.
Treatment of DIC
• Treatment of the
underlying disorder .
• Transfusion support of
Red Blood Cells or
Fresh Frozen Plasma
(FFP) to replace
coagulation factors.

9. Thrombotic
Thrombocytopenic
Purpura (TTP)-
Hemolytic Uremic
Syndrome (HUS)

10. TTP-HUS (small-vessel platelet-rich thrombi)
 Acute syndromes with abnormalities in multiple organ systems and
evidencing microangiopathic hemolytic anemia and thrombocytopenia.
 uncommon.
 HUS is thought by some to be the same condition as TTP because both
disorders have the same underlying pathology.
 HUS is more often associated with renal failure.(diarrhea/ Shiga toxin-
producing Escherichia coli (E. coli O157:H7))
 TTP with neurological manifestations.
 precipitating factors including:
 infection,
 Carcinoma,
 pregnancy.

11. TTP-HUS pathophysiology
• In normal plasma ultra-large vWF is cleaved into smaller fractions
(necessary for balanced coagulation activity) by an enzyme
processed by the gene, ADAMTS13.
• In patients with TTP, the enzyme activity is < 5% of normal.
• These ultra-large VwF molecules get into circulation, resulting in
excessive platelet aggregation and microvascular thrombus formation.

12. ● Thrombocytopenia (<20 x 109/L)
● TTP< HUS.
•
● Schistocytes in blood film
◦ Microangiopathic hemolytic anemia
● LDH
● Serum bilirubin
● Reticulocyte counts
● Normal Prothrombin time (PT).
● Normal activated partial
thromboplastin time (aPTT).
TTP-HUS
LABORATORY
FINDING

13. Treatment of TTP
• Therapeutic plasma exchange (TPE).
• Fresh frozen plasma (FFP), to compensate ADAMTS13 deficiency and
lessen down the effect of autoantibody against the enzyme.
• Exchange takes place over several days until the patient's platelet count
stabilizes above 100 x 109/L.
• TPE has decreased TTP mortality rate from 90% to 15% since the treatment
first came into use as the standard primary treatment of TTP in the 1970's.

14. Immune
thrombocytopenia

15. Immune thrombocytopenia purpura
 The autoantibodies are directed
against GPIIb/IIIa (fibrinogen receptor)
and the complex GPIb/IX (von
Willebrand factor receptor).
 Antibody-coated platelets are
subsequently removed by the spleen.
 platelet production may also be
impaired (megakaryocyte injury by the
autoantibodies).
 common viral or bacterial infection OR
failure of T-regulatory cells.

17. ITP possible treatment
 Treatment guidelines recommend that patients receive treatment if they have any of the
following:
• Significant bleeding risk.
• <20 x 109/L platelets and moderate bleeding.
• <10 x 10 9/L platelets with no bleeding symptoms.
 Corticosteroids are effective treatments for 50-80% of individuals with either acute or
chronic ITP.
 Intravenous immunoglobulin (IVIG) contains the pooled immunoglobulin G (IgG)
immunoglobulins from the plasma.
 Splenectomy may be a last resort treatment for chronic ITP sufferers if their platelet
counts are below 30 x 109/ L or if symptoms warrant it.

18. ITP possible treatment/ CONT…..
 Intravenous immunoglobulin (IVIG) contains the
pooled immunoglobulin G (IgG) immunoglobulins
from the plasma.
 Blockade of macrophage Fc receptors is
considered the primary mechanism of action of
immune globulin in persons with ITP.

19. Drug Induce Thrombocytopenia
 Thrombocytopenia develops within
hours of drug exposure if the patient has
been previously exposed to the drug.
 Within one to two weeks of daily
exposure.
 Resolves within five to seven days of
drug discontinuation.

21.  A small percentage of patients exposed to heparin (<5 percent) may develop
heparin-induced thrombocytopenia (HIT).
 New onset thrombocytopenia in a patient exposed to heparin within the prior
5 to 10 days.
 platelet count drop >50 percent of baseline.
 necrotic skin lesions at sites of heparin injection; and acute systemic reactions
after intravenous heparin administration.
Heparin-induced thrombocytopenia

22. PATHOPHYSIOLOGY
 IgG antibodies directed against
heparin complexed with platelet
factor 4 (PF4).
 Platelet Fc receptors bind the
antibody heparin-PF4 immune
complex.
 Platelet activated & release
micropartical, which contribute to
thrombosis.
 Macrophage removal
 Platelet consumption by thrombosis

23. PATHOPHYSIOLOGY
 PF4 binds to heparin sulfate on
vascular
 Antibody binding to this complex,
injure the endothelium, promotes
thrombosis.

24. Treatment
 Immediate discontinuation of heparin and
administration of a non-heparin anticoagulant.

25. Thrombocytopenia
in pregnancy

26. Incidental thrombocytopenia during pregnancy,
(Gestational thrombocytopenia)
 Approximately 5 percent develop incidental thrombocytopenia.
 Defined by the following five criteria:
 Mild and asymptomatic thrombocytopenia. Platelet counts are typically >70,000/microL, with
approximately two-thirds between 130,000 and 150,000/microL.
 No past history of thrombocytopenia (except possibly during a previous pregnancy).
 Occurrence during late gestation.
 No association with fetal thrombocytopenia.
 Spontaneous resolution after delivery.

27. When to concern thrombocytopenia
in pregnant woman?
•?? ITPplatelet count is less
than 70,000/microL.
• renal insufficiency, hypertension, microangiopathic
hemolytic anemia.
• ??the hemolysis, elevated liver
enzymes, low platelet count (HELLP) syndrome,
??preeclampsia, or ??thrombotic
thrombocytopenic purpura (TTP).
• Severe thrombocytopenia.
• Thrombocytopenia
accompanied by other
findings during pregnancy.

28. Thrombocytopenia
In Neonates

29. Etiology of
neonatal
thrombocytopenia
Increased destruction
( Most common)
• Neonatal alloimmune
thrombocytopenia.
• Autoimmune
thrombocytopenia.
• Drug-related destruction.
• Sequestration and
trapping – Hypersplenism
• Platelet activation and
consumption – DIC
decreased production
of platelets
• Preeclampsia
• Genetic disorders
• Bone marrow infiltrative
diseases
Increase
destruction and
decrease
production/others
• bacterial, viral, or
fungal infection
• Perinatal asphyxia
• Dilution

30. Neonatal Allo-immune Thrombocytopenia
 when fetal platelets contain an antigen
inherited from the father that the mother
lacks.
 The mother forms IgG (immunoglobulin G)
class antiplatelet antibodies against the
"foreign" antigen.
 IgG cross the placenta and destroy fetal
platelets that express the paternal
antigen.
 Incidence — 1 in 1000 to 10,000 births.

31. Symptoms Seen in Thrombocytopenia
If a platelet count is less than 30 x 109/L
bruisingPetechiaePurpuraEpistaxis
Bleeding into the central nervous system may occur
If a platelet count is less than 10 x 109/L

32. Do all thrombocytopenic patients have symptoms?
asymptomatic,
isolated thrombocytopenia
?? (ITP)
Symptoms varies depend on
severity
??autoimmune disorders,
??nutrient deficiencies,
thrombotic microangiopathies,
acutely ill, hospitalized
patients
platelet consumption,
??bone marrow suppression
from sepsis/infection, or DIT

33. When to worry about bleeding?
 Patients with severe thrombocytopenia.
 Prior bleeding at a similar platelet count and the presence of wet purpura (mucosal
membranes).
 The following may be used as guides, but should not substitute for clinical judgment based
on individual patient and disease factors:
 Surgical bleeding generally with platelet counts <50,000/microL (<100,000/microL for
some high-risk procedures such as neurosurgery or major cardiac or orthopedic
surgery).
 Severe spontaneous bleeding is most likely with platelet counts <10,000/microL.

34. When to worry about thrombosis?
 Heparin-induced thrombocytopenia
 Disseminated Intravascular Coagulation
 TTP-HUS
 Paroxysmal nocturnal hemoglobinuria

35. Initial questions in thrombocytopenia
evaluation
When a patient presents with unexpected thrombocytopenia, we
want to know:
 Is the thrombocytopenia real?
 Is the thrombocytopenia new?
 Are there other hematologic abnormalities?

36. PTCP

37. What
Dose
PTCP
Stands
for?
Pseudo-
thrombocytopenia

38. Pre-analytic Variable Leading to False
Thrombocytopenia (PTCP)
 The platelet count is only as good as the sample collected.
 for coagulation purposes should be inverted 5-10 times for proper mixing of
the anticoagulant and the blood. If the tube is not mixed, small fibrin clots
may form, causing a falsely decreased platelet count.

39. Analytic Variable Leading to False
Thrombocytopenia
• Cell cytoplasmic
fragments
• Microcytic RBCs
Giant platelet
Platelet Clumps
spurious
increase in
the platelet
count
spurious
decrease in
the platelet
count

41. Platelet Clumps &
platelet satellitism

42. Case study 1
 A 57-year-old retired farmer with no personal or family history of bleeding
was found to have thrombocytopenia on routine blood work.
 He had a history of type 2 diabetes, hypertension, hyperlipidemia, and
osteoarthritis. Medications included perindopril, insulin glargine, aspirin,
metformin, ibuprofen, and oregano oil. Physical examination was normal.
 His complete blood count (CBC):
 WBC: 9.4 × 109/L,
 Hemoglobin: 16.0 g/dL,
 Platelets: 10 × 109/L by automated counter.

43. CONT…
 A peripheral blood film showed clumping of platelets (blood smear).
 A bone marrow aspirate and biopsy, initially performed to rule out
myelodysplasia, was normal with normal-appearing megakaryocytes in
adequate numbers.

44. Diagnosis
 The patient was diagnosed with pseudo-
thrombocytopenia.
 No further treatment or blood work was
required.

45. Case Conclusion
 Unrecognized pseudo-thrombocytopenia may result in
unnecessary diagnostic testing and clinical concern.
 A microscopic examination can identify platelet clumping and
repeat CBC tests using a different anticoagulant can affirm the
diagnosis.

46. EDTA-dependent agglutinin/ plts Clumps
 Approximately 0.1 percent of individuals
have EDTA-dependent agglutinins.
 platelet membrane (GP) IIb/IIIa becomes
exposed by EDTA-induced dissociation
of GPIIb/IIIa.
 "naturally occurring" platelet autoantibody
directed against a concealed epitope on
platelet membrane glycoprotein
(GP) IIb/IIIa

47. EDTA-dependent agglutinin/ plts satellitism
 platelets may rosette around
WBCs.
 presence of an EDTA-
dependent antibody with
dual reactivity against
GP IIb/IIIa and the neutrophil
Fc gamma receptor III.

48. What to do?
 If platelet clumping is observed, the platelet count is repeated
using heparin or sodium citrate as an anticoagulant in the
collection tube.
 If citrate is used, the platelet count should be corrected for dilution
caused by the amount of citrate solution.
 multiplying the platelet count that is obtained from the automated
analyzer by 1.1.
 no such correction is needed for heparin.

49. Platelets
Collection &
Transfusion

50. Platelets Collection
Isolation from donated blood
 One unit of platelets contain 7 x
1010 platelets.
Apheresis from a donor
 equivalent of six or more units of
platelets from whole blood

51. Indication of Platelets Transfusion
 Actively bleeding patient.
 Preparation for an invasive procedure.
 Prevention of spontaneous bleeding.

52. Platelets Count Increment
 Following a platelet transfusion, the platelet count should rise, with
a peak at 10 minutes to one hour and a gradual decline over 72
hours.
 Six units of pooled platelets or one apheresis unit should increase
the platelet count by approximately 30,000/microL in an adult of
average size.
 Platelets express ABO antigens on their surface, as well as HLA class
I antigens. They do not express Rh or HLA class II antigens.
 ABO and HLA compatible platelets appear to cause a greater
platelet count increment in the recipient.

53. Take Home Points
 Thrombocytopenia is the drop in platelet count below the lower limit of
normal <150,000/microL.
 Thrombocytopenia can be mild, moderate or severe depend on the platelet count.
 Thrombocytopenia results from decrease of platelets production, increase platelets
destruction, sequestration of platelets in the spleen or Dilution.
 Identification of thrombocytopenia cause is highly important to avoid the undesirable
consequences ( bleeding or thrombosis).
 Pseudo-thrombocytopenia result from either Incompletely mixed, inadequately anti-
coagulated samples or from EDTA- dependent agglutinin.
 Pseudo-thrombocytopenia should be recognized to avoid unnecessary diagnostic testing
and clinical concern.
 Platelet transfusion used as prophylactic or therapeutic purposes.
 Transfusion of single adult dose of platelets ( six units/ one apheresis unit) should increase
platelet by 30,000/µl.

54. References
 http://www.uptodate.com/contents/approach-to-the-adult-with-
unexplained-thrombocytopenia.
 http://www.uptodate.com/contents/drug-induced-thrombocytopenia.
 http://www.uptodate.com/contents/causes-of-neonatal-
thrombocytopenia.
 http://www.uptodate.com/contents/thrombocytopenia-in-pregnancy.
 http://www.uptodate.com/contents/clinical-and-laboratory-aspects-of-
platelet-transfusion-therapy.
 www.medialab.com

58. DIC Pathophysiology