2. The granular appearance of the platelets helps to distinguish them from artifact in the
peripheral smear
3. Brief history of the platelet
• Osler, Hayam, and Bizzozero identified small particles in the
blood, these were believed to be either bacteria or red cell
fragments
• James Homer Wright “Wright Stain” identified platelets as a
distinct hematopoetic component arising from
megakaryocytes
• William Duke in 1910 described 3 patients with low platelet
counts that had hemorrhagic disease
• Duke created a venous shunt from a normal donor to a
thrombocytopenic recipient and showed that the platelet
count could rise and the bleeding would cease
4.
5. Figure ; Platelets can be seen as individual structures forming on the periphery of this
megakaryocyte
6. Platelet Kinetics
• Normal circulating platelet count
– 150K to 400K (150,000/ul to 400,000/ul )
– 90 to 300 K in people of Mediterranean descent
• 1/3 of platelets are sequestered in the spleen
• lifespan of a platelet is 7 to 10 days
• 15 to 45 K platelets are produced daily to maintain
steady state
7. .
EDTA may produce this effect causing a spurious decrease in the platelet count
8.
9. Thrombopoietin (TPO)
• TPO is the primary regulatory protein in the
production of platelets
• TPO gene is on chromosome 3
• TPO is expressed in the liver, kidneys, and smooth
muscle cells
• Has a plasma half life of 30 hours
• The receptor for TPO is c-MPL which is present on
the megakaryocytes and platelets
• TPO rises with platelet fall and declines as the megakaryocyte
and platelet mass increase
10. why we are worried about
Thrombocytopenia ?
• 1/3 of all Hematology Consults in a General Hospital are for
thrombocytopenia
• 5 -10% of all hospital patients are thrombocytopenic
• 35% patients in the ICU are thrombocytopenic
• Thrombocytopenic patients in the hospital suffer a two fold
greater mortality rate than those who are not
11. Practical Importance of Assessing
Thrombocytopenia..
The primary reason for evaluating
thrombocytopenia is
• To assess the risk of bleeding
• To assess the presence of serious underlying
disorders (malignancy ,TTP, HIT )
12. Relation of bleeding risk and platelet
count
– < 20 K …..increased risk of bleeding
– 20 – 50 K ….. rarely have increase risk of spontaneous
bleeding but increase risk of bleeding from procedures
– 50 --100 K ……no increased risk of spontaneous bleeding
and can undergo most procedures
13. Clinical manifestations of thrombocytopenia
• Petechiae (not seen in haemophilia or VWD)
• Pupura
• Echymoses
• Mucosal bleeding
• Menorrhagia
• Intracranial bleeding (uncommon but the most feared)
14. Clinical manifestations of thrombocytopenia
• Some times
thrombosis
Infact low platelet is a manifestation of
thrombosis
15. Petechiae
Do not blanch with pressure
(cf. angiomas)
Not palpable
(cf. vasculitis)
(typical of platelet disorders)
16.
17. Thrombocytopenia
sequestration
in spleen
• Production
– Marrow
Damage
• Aplasia
• Drugs
• Malignancy
– Congenital
Defects
– Ineffective
Production
• B12 def
• Folic acid def
• Destruction
– Non
Immune
• DIC
• TTP
• HELLP
– Immune
• ITP
• HIT
• SLE, AIDS
• TTP
20. Congenital Thrombocytopenia
• Reasons to Suspect
• Persistence of neonatal thrombocytopenia
• onset of bleeding symptoms in childhood
• Family history of thrombocytopenia or mucocutaneous
bleeding
• Platelet count unresponsive to typical treatments for ITP
21. Congenital Thrombocytopenia
Low MPV Normal MPV Large MPV
W A S (X linked) FPD/AML Bernard Soulier
TAR Platelet type vWD
AT/RS MYH9
CAT Grey Platelets
11q- disorder GATA1
Treatment of Bleeding
• platelets
• DDAVP
• Recombinant FVIIa
23. ITP
(Immune Thrombocytopenic Purpura)
• Isolated thrombocytopenia with no clinically
apparent associated conditions or other causes of
thrombocytopenia
• high prevalence disease
• 16 to 27 per million per year
• Incidence increases with age
• Female predominance at age < 60 but not over the
age of 60
• It is generally abrupt in onset with children
• It can have an insidious onset.
24. Types of ITP according to etiology
• ITP..(idiopathic)
• Neonatal Thrombocytopenia
Associated with Maternal ITP( transfer of IgG),Drug-Related
• Drug Induced
Quinidine, Quinine, Sulfa, Gold Salts, Abx (Vanco etc), Heparin
• Lymphoma associated
• Autoimmune disorders
Thyroiditis, SLE, Colitis, Sarcoidosis
• Infections
HIV, Rubella, viral Hepatitis, CMV,
• Pos-transfusion Purpura
25. Types of ITP according to clinical
presentation
• Acute ITP
• Chronic ITP
• Resistant ITP
• Refractory ITP
26.
27. Pathogenesis of ITP
• Increased platelet destruction caused by antiplatelet
antibodies
• +
• Lack of compensatory response by megakaryocytes
due to suppressive effect of antiplatelet antibodies
28. Features of Acute ITP
• Peak age Children (2-6 yrs)
• Female:male 1:1
• Antecedent infection Common
• Onset of symptoms Abrupt
• Platelet count at presentation <20,000
• Duration 2-6 weeks
• Spontaneous remission Common
29. Features of Chronic ITP
• Peak age Adults (20-40 yrs)
• Female:male 3:1
• Antecedent infection Rare
• Onset of symptoms Abrupt-indolent
• Platelet count at presentation <50,000
• Duration Long-term
• Spontaneous remission Uncommon
30. Diagnosis of ITP
• Features consistent with the diagnosis of ITP
– Thrombocytopenia with normal or slightly large platelets
– Normal RBC morphology and number (may have
associated iron def or thallasemia etc.)
– Normal white cell number and morphology
– Splenomegaly rare
• Features not consistent with the diagnosis of ITP
– Giant platelets
– RBC abnormalities ie schisotocytes
– Leukocytosis or Leukopenia
31. Laboratory evaluation of ITP
• Not Much !!!!!!!
– Platelet associated immunoglobulin reflect
plasma concentration
– Bone Marrow not very helpful as initial test
• May be helpful in patient over 50 years and concerned
about MDS
• If patient has failed initial treatment and diagnosis is in
question
– TSH and HIV test helpful,
– Peripheral Smear helpful
32. Management of ITP
• Most patients with ITP do not have clinically
significant bleeding
– Risk of intracranial bleed 0.1 to 1% (This is an
overestimate)
– Wet Purpura ie epistaxis, gingival bleeding is a risk
factor for major bleeding
In asymptomatic patients with platelets counts
greater then 20 K observation is reasonable
33. Management of Acute ITP
• First line therapy
1. Steroids
– Prednisone 1mg/kg/day , tapering over 2 months
– Decadron 40 mg/day x 4 days
– Solumedrol 1 gram/day x 3 days
2. Antibodies
– IVIG 1 gram/day x 2 days
– Anti-D 50 mcg/kg IV x1
34. Management of Acute ITP
• Second line therapy
1. Immunomodulation .
a. anti CD 20. 375mg/m2/week x 4 injections
b. Azathioprine 50-200 mg /d
c. Cyclosporine 50-200 mg/d
d. Danazol 200-800 mg/d
e. Vincritine 2mg /week x3 injections
2. Splenectomy
3. Eltrombopag 25-75 mg /day
35. Management of Chronic ITP
• Splenectomy
– Immunize with Pneumovax, Hib, Meningococcal
• Chronic Anti-D therapy
– Does not put the disease in remission
• Immunomodulation eg Rituximab
• Eltrombopag ,TPO analogue
• Observation
36. Management in pregnancy
• Gestational Thrombocytopenia
– Platelet count >70K, occurs late in gestation, not
associated with fetal thrombocytopenia, resolves
after pregnancy
• ITP in pregnancy
– Treat if symptoms, intermittent IVIG, Prednisone,
anti-D
– Epidural anesthesia appears safe if platelet count
> 50K
– Monitoring for neonatal thrombocytopenia
39. Lab findings of TTP
• Severe thrombocytopenia <30 K to 75 -100 K
• Hemolytic anemia with several fragmented red cells
in high power oil (>1% total number of RBC
• Renal Abnormalities ,may be subtle ,initially
• Markedly elevated LDH
• Initially coagulation studies are normal
40. Figure 1. Peripheral smear showing microangiopathic hemolytic features with numerous RBC
fragments (helmet cells/schistocytes)
41. Figure 2. Peripheral smear showing RBC fragmentation consistent with a microangiopathic
hemolytic process
43. Treatment of TTP
• Daily plasma exchange with either FFP or
cryopoor FFP (45 to 55 cc/kg/day) reduces
mortality from 100% to 20%
• Steroids
• Platelet tx …?
• no …..why?????
44. Heparin Induced Thrombocytopenia
• Described in 1958 by Rodger Weismann and
Richard Tobin after extracting platelet fibrin
thrombi that formed after 1 to 2 week course
of heparin
• HITT is the presence of a multimolecular
complex between platelet factor 4, and
heparin
• HITT is associated with thrombosis despite
profound thrombocytopenia
45.
46. Clinical Features of HITT
• Timing
– Onset between days 5 and 10 after heparin
initiation
– Rapid onset if previously exposed to heparin
• Thrombocytopenia nadir between 15 to 150 K
• >50% develop a new thrombosis both venous and
arterial
• Absence of petechia
47. Diagnosis of HITT
• Clinical Suspicion (ie greater then 50% drop in
platelets in the setting of heparin use)
• Laboratory Studies
– Platelet Activation Studies (Complicated and
physiologic)
– PF4/Polyanion Studies (Less time consuming but
not necessarily physiologic)
• Even without evidence of thrombosis patient should
get lower extremity dopplers
48. Treatment of HITT
• Removal of all Heparin products
• Begin direct thrombin inhibitor (DTI) (Argatroban or
Refludan)
• Treat with DTI until platelet count normalizes then
may begin anticoaguation with warfarin
• Fondaparinux (Arixtra) is a reasonable agent to use
for DVT prophylaxis in patient with history of HIT
54. Treatment
• FFP and platelet transfusions in bleeding
• Trigger for prophylactic platelet tx is higher
than in ITP
• Why ?
55. Macrovascular thrombosis
• Macrovascular thrombosis eg DVT is also a
cause of low platelet s
• D dimer
• Doppler studies
• Anticoagulation with careful monitoring of
counts
• Rise in plt count is indicater of …..
56. Practical Aspects for the management of
thrombocytopenia
• What is an adequate platelet count for procedures?
– Routine Dentistry >10K
– Dental Extraction >30K
– Regional Dental Block >30K
– Minor Surgery >50K
– Major Surgery>80K
– Epidural is okay at platelet count 50K for patient with ITP
• The target platelet count for a bleeding patient is
generally >40K
• Prophylactic platelet transfusions trigger is < 10K
57. Treatment options for the Bleeding Patient
• Red blood cells
• Platelet transfusions
• Fresh frozen plasma
• Cryoprecipitate
• Amicar
• DDAVP
• Recombinant Human factor VIIa
58. 1.PRBC tx
• Laminar blood flow is disturbed at HCT <30%,
• so It is important to raise HCT by PRBC tx ,in
severely anemic and thrombocytopenic
patients.
60. Platelet transfusions - complications
• Transfusion reactions
– Higher incidence than in RBC transfusions
– Related to length of storage/leukocytes/RBC mismatch
– Bacterial contamination
• Platelet transfusion refractoriness
– Alloimmune destruction of platelets (HLA antigens)
– Non-immune refractoriness
• Microangiopathic hemolytic anemia
• Coagulopathy
• Splenic sequestration
• Fever and infection
• Medications (Amphotericin, vancomycin, ATG, Interferons)
61. Aminocaproic acid (Amicar)
• Mechanism
– Prevent activation plaminogen → plasmin
• Dose 50mg/kg po or IV q 4 hr
• Uses
– Primary menorrhagia
– Oral bleeding
– Bleeding in patients with thrombocytopenia
– Blood loss during cardiac surgery
• Side effects GI toxicity,Thrombi formation
63. message
• Treatment of thrombocytopenia is according to cause
• It is important to know spleen size of thrombocytopenic
patient
• Look at LDH
• Every thrombocytopenia is not ITP
• Every ITP does not need tm