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DIAGNOSIS AND MANAGEMENT OF
PLATELET DISORDERS
T. Kozak
Lecture for summer semestr 2013
Overview
• Platelets
– Normal Physiology
– Categories of Thrombocytopenias
• ITP
• TTP
• HIT
• Thrombocytopathy
• Thrombocytosis
Normal PhysiologyProduction and Number
 Platelets are normally made in the bone marrow
from progenitor cells known as megakaryocytes.
 Normal platelet lifespan is 10d. Every day, 1/10
of platelet pool is replenished.
 Normal platelet count is between 150 and 450 x
109/l.
Platelet Response
•Platelets adhere
to vessel wall, then
aggregate, leading
to formation of a
platelet plug
•Platelets provide phospholipid scaffold
for thrombin generation.
Platelets physiology
PLT contain: mitochondria, glycoprotein containing granules, lysosomes,
and:
-granules: fibrinogen, von Willebrand f. (vWF) fibronectin, f.
V, PLT f. 4, -thromboglobulin, thrombospondin, PDGF
2 types of granules:
dense granules: serotonin, calcium, ADP, ATP
PLT surface:
GpIb: receptor for vWf
GpIIb-IIIa: receptor for fibrinogen, fibronectin,
vitronectin
Platelet disorders
Thrombocytopenia
Thrombocytopathy
Combined
Thrombocytosis
Platelet disorders
Thrombocytopenia
Acquired
Thrombocytopathy
Combined
Congenital/inherited
Platelet disorders
Thrombocytopenia
Acquired
Thrombocytopathy
Combined
Congenital/inherited
Symptoms: Asymptomatic
Bleeding
Thrombosis
Thrombocytopenias
PLT < lower limit of the range, usualy < 130 x 109/l
ITP definition: PLT < 100 x 109/l
Severe thrombocytopenia: PLT ≤ 20 x 109/l
Congenital (rare): Fanconi´s s., Wiskott-Aldrich´s s.,
May-Hegglin a., Bernard-Soulier´s s.,
amegakaryocytic trombocytopenia. Often include
thrombocytopathy
Acquired: frequent
Thrombocytopenia:
5 broad categories of
causes
• Pseudothrombocytopenia
• Underproduction (AL, MDS, congenital TP, infiltration of
bone marrow)
• Peripheral Destruction or consumption (ITP, TTP, DIC)
• Splenic sequestration (hypersplenism)
• Other: dilution (multiple erytrocyte transfusions etc.)
Pseudothrombocytopenia
•
Pseudothrombocytopenia
• Artificial platelet clumping in the tube with EDTA
• Platelet clumping is of no clinical significance
• No increased risk of bleeding or clotting
• How to confirm:
1. Clumps in light microscopy
2. Repeated blood count test using citrate or Heparin as
anticoagulant agent reveal normal PLT count
Thrombocytopenia due to
Peripheral Destruction
 Non-immune mechanisms:
 Platelet activation and consumption:
e.g. TTP and DIC
 Immune Mechanisms: ITP
 antibody-mediated platelet destruction
 may be primary, secondary, or drug-induced.
ITP – Immune Thrombocytopenia (in the
past: „Idiopathic Thrombocytopenic
Purpura“)
 Definition: isolated thrombocytopenia with no clinically
apparent associated conditions or other causes of
thrombocytopenia.
 Etiology: autoantibodies directed against platelets coat
platelet surface. IgG-coated platelets are taken up by RE
system.
 Incidence: approximately 100 per million; half of these are
children. In adults, two peaks:
 one are young (<40) with female predominance,
 one are older (>60), no gender predominance.
ITP – Immune Thrombocytopenia (in the
past: „Idiopathic Thrombocytopenic
Purpura“)
 Definition: isolated thrombocytopenia with no clinically
apparent associated conditions or other causes of
thrombocytopenia. PLT < 100x109/l
 Etiology: autoantibodies directed against platelets coat
platelet surface. IgG-coated platelets are taken up by RE
system.
 Incidence: approximately 100 per million; half of these are
children. In adults, two peaks:
 one are young (<40) with female predominance,
 one are older (>60), no gender predominance.
The most common cause of thrombocytopenia
ITP: terminology
 Newly diagnosed ITP: within 3 months from
diagnosis
 Persistent ITP: between 3 to 12 months from
diagnosis.
 Chronic ITP: lasting for more than 12 months
Severe ITP
Presence of bleeding symptoms at
presentation sufficient to mandate treatment, or
occurrence of new bleeding symptoms requiring
additional therapeutic intervention with a
different platelet-enhancing agent or an
increased
Autoantobodies in ITP: 75%
 GpIIb/IIIa (CD41) (αβ-integriny)
 GpIbIX (CD42)

HIV positive: anti-IIIa
12- lipooxygenase
Arach. acid
NADPH oxidase
Superoxides + free 02 radicals
Autoantobodies in ITP: 75%
 GpIIb/IIIa (CD41) (αβ-integriny)
Opsonisation
ADCC
 GpIbIX (CD42)

HIV positive: anti-IIIa
12- lipooxygenase
Arach. acid
NADPH oxidase
Ab mediated autocytolysis
Superoxides + free 02 radicals
ITP – pathogenesis
Shorter PLT lifespan
Antibodies
+
differentiation & maturation of MGKC
T LYMPHOCYTES
apoptosis of megakaryocyte
Relative thrombopoetin deficit
in ITP
400
1750
1500
300
1250
1000
200
750
500
100
eTPO (pg/mL)
PLT count (x 109/L)
Mean PLT count (x 109/L)
Maximal eTPO level (pg/mL)
250
0
0
Normal
(n=96)
Aplastic
anemia
ITP
(n=45)
(n=23)
Podle: Nichol. Stem Cells 1998;16(suppl 2):165–175
23
ITP = increased PLT
destruction and suboptimal PLT
production
Adapted from: Kuter et al. Thrombopoiesisand Thrombopoietins: Molecular, cellular, preclinical and clinical biology. Totowa, NJ: Humana Press Inc;1997
Role of lymphocytes in
pathogenesis of ITP
• Cytokine profile TH1/Th0 corelates with disease
activity
• Regulatory T cells reduced + not functional
• T cells can directly influence MGKCs and decrease
PLT production
• 25% ITP without detected antibodies: „T cell -
mediated toxicity“
B lymfocytes in ITP
• Autoantibodies production
BAFF (B cell activating factor): TNF family
- Produced and released by monocytes a T lymphocytes
- increases lifespan of B and T lymphocytes decreases
apoptosis
- BAFF itself increases apoptosis in thrombocytes
- mRNA BAFF in ITP patients s ITP is increased
Monocytes and Tregs in ITP
TGFβ
CD4
Ag
CD25
Foxp3
MONO
PLT
+
IL-2
CD28
Ig
CD4
TPO-R A
ITP - Diagnosis
 ITP is a Diagnosis of Exclusion
(diagnosis per exclusionem)
 No specific laboratory test can confirm
diagnosis of the ITP
 Need to exclude other causes of
thrombocytopenia
Primary/secondary ITP
SLE, systemic lupus erythematosus; APS. antiphospholipid antibody syndrome; CVID, common variable immunodeficiency;
CLL, chronic lymphocytic leukaemia; ALPS, autoimmune lymphoproliferative syndrome
Cines D et al. Blood2009;113:6511–6521
Primary/secondary ITP
SLE, systemic lupus erythematosus; APS. antiphospholipid antibody syndrome; CVID, common variable immunodeficiency;
CLL, chronic lymphocytic leukaemia; ALPS, autoimmune lymphoproliferative syndrome
Cines D et al. Blood2009;113:6511–6521
Evaluation of Patient with Low
Platelets
 History
 Has the patient ever had a normal platelet count? Family
history
 Carefully review medications, including Over the counter
meds.
 Antibiotics, quinine, anti-seizure medications
 Ask about other conditions which may be associated with low
platelets
 Liver Disease/hepatitis
 Thyroid Disease - both hypo- and hyper Infections: viral, rickettsial
 Pregnancy
 Consider other conditions which may be associated with ITP
 Lupus erythematosus, CLL, lymphoma, antiphospholipid
syndrome
Evaluation of Patient with Low
Platelets
 Physical
 Evaluate for lymphadenopathy and splenomegaly
 Look for signs of bleeding
 Blood blisters and oral petechiae, ie “Wet Purpura”
 best harbinger of intracranial hemorrhage
 Laboratory Data
 Other blood counts should be normal.
 Check B12 and folate levels.
 Look at peripheral blood smear to exclude pseudothrombocytopenia,
exclude TTP (especially if anemia also present.)
 Send coagulation screens (PT/PTT) to exclude DIC
 Send HIV, hepatitis serologies and TSH
 H. pylori: antigen in stools or breath urease test
 Consider doing a bone marrow biopsy and smear
 Obligatory in pts >60 years of age
 Megakaryocytes should be present.
ThrombocytopeniaHow low is too low?
 100,000 - 50,000: no symptoms
 No treatment generally required.
 50,000 - 20,000: first symptoms
 Generally need to begin therapy
 20,000-10,000: may be life-threatening
 Sometimes requires admission
 <10,000: risk for spontaneous intracranial
hemorrhage, usually requires inpatient
treatment
Need for PLT counts if normal PLT
function
Dental prophylaxis (descaling, deep cleaning) ≥20–
30 × 109/l
Simple extractions ≥30 × 109/l
Complex extractions ≥50 × 109/l
Regional dental block ≥30 × 109/l
Minor surgery ≥50 × 109/l
Major surgery ≥80 × 109/l
Major neurosurgery ≥100 × 109/l
Vaginal delivery: 50 x 109/l
ITP: Serious and fatal
bleeding depending on age
Bleeding risk in 5 years
100
90
Fatal
80
|Non- fatal
70
60
50
40
30
20
10
0
<40
40–60
Age
Podle: Cohen et al. Arch Intern Med 2000;160:1630–1638
>60
Management of ITP: Asymptomatic
Adult
 If platelet count is >40-50 x109/l, no therapy
is required. Check platelet counts at
designated intervals.
 If platelet count is < 20-30 x109/l , begin
therapy with corticosteroids.
 Stop all NSAIDS and ASA to improve
platelet function.
Corticosteroids in ITP
1. Prednison: 0,5 – 2mg/kg of BW/day
1. Or: Methylprednisolone i.v. 1g/D for 3-5 days
followed by oral Prednison
2. Or: Dexamethason 40mg p.o.(i.v.) D1-4
CAVE: in pregnancy only Prednison 20mg/day and
less and No corticosteroids in the 1st trimester!!
Initial Management of ITP
Adult with Symptomatic Purpura
 If platelet count is >10, treat with prednisone
alone
 If suspicious intracranial or GI bleeding (ulcer
etc.), treat with itravenous immunoglobulins
IVIg 1g/kg/d x 2d. - may require admission
 If patient has severe bleeding and life is in
danger: may need platelet transfusions
 Along with prednisone, add Calcium and
Vitamin D to prevent bone loss.
Subsequent Management of ITP
Adult with Symptomatic Purpura
 Follow platelet counts daily until >20, then can
d/c patient with close follow-up
 Once platelet count normalizes, commence a
slow steroid taper over 6-8 weeks.
 1/3 of adults will go into remission.
 2/3 of patients will relapse during or after steroid
taper.
Management of Relapsed ITP
• Once the patient relapses, may need to use steroids to
•
•
1.
2.
3.
increase the platelet count out of the danger range,
but THIS CANNOT SUBSTITUTE FOR DEFINITIVE
THERAPY.
Prednisone is now a crutch to support a dangerously
low platelet count. Long corticosteroid treatment
should be avoided.
Options today include:
splenectomy, if contraindicated (including patient´s
refusal):
TPO mimetics (Romiplostim, Eltrombopag).
In the past: intermittent treatment with anti-D
immune globulin.
Management of Relapsed ITP:
Splenectomy
 Splenectomy is effective in 2/3 of patients,
leading to normal platelet counts.
 Can be performed via open method or
laparoscopically.
 Need to vaccinate against encapsulated
bacteria 2 weeks before procedure.
 May need steroids and/or IVIg before
procedure to boost platelet counts
preoperatively.
Management of Relapsed ITP
Anti-D Immune Globulin
 Can be used as a substitute for IVIg for maintenance






therapy
Especially useful in patients with contraindications to
splenectomy.
Coats red cells with IgG and allows red cells to serve
as decoy for splenic macrophages.
Patient must be Rh positive.
Not effective after splenectomy.
Designed to cause hemolytic anemia--Hgb may drop
as much as 3g/dl.
Intermittent dosing may allow patients to avoid
splenectomy.
Romiplostim: structure
Fc carrier - part of Ig
§
Peptide domain
Podle: Bussel et al. N Engl J Med 2006;355:1672–1681
Bussel et al. N Engl J Med;355:1672–1681. Copyright © 2006 Massachusetts Medical Society. All rights reserved.
Dlouhodobá odpověď na Romiplostim (%)
Long lasting response to
Romiplostim vs placebo
80
Placebo
Romiplostim
70
61
60
49
50
38
40
30
20
10
0
0
(p=.0013)
Splenectomized
Podle: Kuter et al. Lancet 2008;371:395–403
5
2
(p<.0001)
(p<.0001)
Not splenectomized
All
Overall response to
romiplostimem
Placebo
Romiplostim
100
Odpověď na Romiplostim (%)
88
83
79
80
60
40
14
20
7
0
0
(p<.0001)
Splenectomized
Podle: Kuter et al. Lancet 2008;371:395–403
(p<.0001)
Not splenctomized
(p<.0001)
All
This article was published in Lancet, 371:395–403, Kuter et al. Efficacy of romiplostim in patients with chronic immune
thrombocytopenic purpura: a double-blind randomised controlled trial. Copyright Elsevier 2008
Pacienti, kteří potřebovali záchrannou léčbu (%)
Need for salvage therapy
Placebo
Romiplostim
100
80
60
62
57
60
40
26
17
20
0
22
(p=.0175)
Splenectomized
Podle: Kuter et al. Lancet 2008;371:395–403
(p=.0004)
Not - splenectomized
(p<.0001)
All
This article was published in Lancet, 371:395–403, Kuter et al. Efficacy of romiplostim in patients with chronic immune
thrombocytopenic purpura: a double-blind randomised controlled trial. Copyright Elsevier 2008
Management of Relapsed ITP
Anti-D Immune Globulin
 Can be used as a substitute for IVIg for maintenance






therapy
Especially useful in patients with contraindications to
splenectomy.
No more available:
Coats red cells with IgG
and allows
red cellscases
to serve
induced
several
of
as decoy for splenic macrophages.
fatal haemolytic
Patient must be Rh positive.
anaemia
Not effective after splenectomy.
Designed to cause hemolytic anemia--Hgb may drop
as much as 3g/dl.
Intermittent dosing may allow patients to avoid
splenectomy.
Case 1
 A 18 y.o. female high school student presents
with a rash over her lower extremities. She had
a viral illness with pharyngitis 3 weeks ago. She
has no other medical problems, and she takes no
medications.
 Physical examination reveals petechiae over the
shins.
 Platelet count is 1 x 109/l (!).
 The patient was admitted to the hospital and
was given DEX 40mg i.v. D1-4
Case 2
 A 40 y.o. man presents with epistaxis to the ER.
He has no medical problems, and he takes no
medications. He works as a big truck driver and
has no occupational exposures. He is married
and has 2 children.
 Physical examination is remarkable only for
epistaxis and scattered petechiae.
 The platelet count is 28 x109/l
 The patient is given PDN 1mg/kg/D as outpatient
but not able to drive a truck
Case 3
 A 46 y.o. woman is found to have a platelet
count of 20 x109/l on routine laboratory testing.
She has some easy bruising and gum bleeding,
but admits to not flossing.
 She has no PMHx, and is on no medications.
She works as gym instructor in a fitness center.
 She is started on 1 mg/kg of prednisone.
Adviced not to do gym lessons.
Management of Refractory ITP
In the past:
 One third of patients will have an inadequate
response to splenectomy.
 Management of these patients is a chalange and
involves accepting that they have a chronic,
incurable condition.
 Target platelet counts should be lower--aim for
about 30K or absence of bleeding.
Today:
Agonists of TPO receptor (TPO agonists):
ROMIPLOSTIM, ELTROMBOPAG
Management of Refractory ITP
In the past:
 One third of patients will have an inadequate
response to splenectomy.
 Management of these patients is a chalange and
involves accepting that they have a chronic,
incurable condition.
 Target platelet counts should be lower--aim for
about 30K or absence of bleeding.
Today:
Agonists of TPO receptor (TPO agonists):
ROMIPLOSTIM, ELTROMBOPAG
If not effective
Treatment of Refractory ITP
 Immunosuppressive agents





Cyclophosphamide
Azathioprine
Rituximab (anti-CD20) – off label
Cyclosporin A
Mycofenolate mofetil
 Adjunct agents
 Danazol
 Examine & Treat Helicobacter pylori
 Other
- Vincaalkaloids
- Alemtuztumab (anti-CD52)
 Stem cell transplant
Drugs Commonly Implicated in
Thrombocytopenia
 Beta-lactam antibiotics.
 Trimethoprim-sulfamethoxazole and other
sulfa drugs.
 Vancomycin.
 Quinine/quinidine.
 Heparin.
 Abciximab (ReoPro®).
 H2 blockers
 If a patient’s platelets fall, ALL unnecessary
drugs need to be stopped.
Case 4
 A 60 y.o. woman presented with bleeding from
her nose and mouth and gums.
 PMHx – Hypertension, DM
 Medications - glucotrol, glucophage, HCTZ,
quinine for leg cramps
 PEx - petechiae over limbs and trunk, blood
blisters in mouth, epistaxis.
 Platelet count 2 x109/l
Case 4
 Pt admitted to hospital, quinine stopped,
patient treated with platelet transfusions and
IVIg.
 Platelet count rose to normal over the next 56 days.
 Eight months later, thrombocytopenia
recurred, and patient admitted to taking
quinine again for recurrent leg cramps.
Drug Induced ITP
 Usually, removing the offending agent is
enough to allow the platelets to rise on their
own.
 If platelets are severely low, platelet
transfusions may be required.
 IVIg is particularly helpful in quinine-induced
ITP.
Case 5
 A 65 y.o. male smoker with a h/o peripheral
vascular disease presented to the ER with
unstable angina. He was admitted to the
hospital and placed on heparin. Platelet count
on admission was 450. Cardiac catheterization
showed severe 3-vessel coronary disease, and
the patient was scheduled for CABG which
occurred on hospital day #7.
 Pre-op platelet count was 200. Post-op platelet
count was 90.
Case 5
 On hospital day #12, the patient developed
acute left leg swelling and a DVT was diagnosed
by ultrasound. Platelet count was 150. The
patient was started on IV heparin. The next day,
he developed a pulseless left leg and had a
platelet count of 30.
 While in vascular radiology, he developed acute
chest pain and suffered a cardiac arrest and
subsequently died. Autopsy showed occlusion
of all of his bypass grafts.
Evan´s syndrome
Immune thrombocytopenia (ITP)
+
Autoimmune hemolytic anemia (AIHA)
Heparin-Induced Thrombocytopenia (HIT)
 Seen in 1-3% of patients treated with heparin
 Usually, 7-10 d after heparin started, platelets fall by at
least 1/3 to 1/2.
 Can occur earlier in patients who have been previously
exposed to heparin, even as SQ injections.
 Less often but still risk exists with low molecular weight
heparin
 Caused by antibodies against the complex of heparin
and PF4. These antibodies activate platelets.
 Can lead, paradoxically, to THROMBOSIS, in up to half
of patients.
 More common in patients with vascular disease
Alternate Presentations of HIT/T

Small drop in platelet count (especially with
skin necrosis)

Earlier onset thrombocytopenia with heparin
re-exposure

Delayed-onset thrombocytopenia/
thrombosis after stopping heparin

Thrombosis after heparin exposure
HIT/T treatment
1. IF PLATELETS FALL ON HEPARIN, STOP
HEPARIN IMMEDIATELY.
2. Stop heparin
3. Stop heparin
4. Use a different anticoagulant
1.
2.
3.
Fondaparinux (Arixtra®)
Lepirudin
Argatroban
Case 6
 A 36 y.o.woman presented in the summer with fever,
cefalea, nausea, vomiting and ppsychomotoric
deterioration. Admitted to ICU of Neurology dept with
provisional dg. Viral encephalitis – tickborn. On
Hospital day 2, hemoglobin and platelet count both
noted to drop. By hospital day 4, Hgb 70 g/l, Plts 12
x109/l. PT/PTT normal. Bilirubin 87 umol/l.
 CSF clear from infection
 The patient recovered after 20 plasmaexchanges.
Thrombotic thrombocytopenic
purpura (TTP)
 Microangiopathic Hemolytic Anemia (MAHA)
 Elevated LDH, elevated bilirubin
 Schistocytes on the peripheral smear
 MUST BE PRESENT
 Low platelets - MUST BE PRESENT
 Fever
 Neurologic Manifestations - headache, sleepiness,
confusion, stupor, stroke, coma, seizures
TTP - etiology
 May be associated with an antibody against or a
deficiency of the protease which cleaves the
ultra-high molecular weight multimers of von
Willebrand’s factor. These very high molecular
weight vWF multimers cause abnormal platelet
activation.
 Can be induced by drugs, including ticlopidine,
quinine, cyclosporine, tacrolimus, mitomycin C.
 Increased incidence with pregnancy or HIV
TTP - Course and Prognosis
 95% fatal prior to therapy, now 5% fatal.
 Treatment relies on PLASMA EXCHANGE +
corticosteroids
 Plasma exchange is superior to plasma infusion, but if PLEX
is delayed, give FFP.
 Remove all inciting agents.
 Platelet transfusions contra-indicated.
 Multiple case reports of stroke and/or death during or
immediately after platelet transfusion.
 Can consider giving if life-threatening hemorrhage is
present, but avoid routine platelet transfusions.
 Secondary measures if no response to plasma
exchange include splenectomy, vincristine
HUS - Hemolytic Uremic Syndrome
 Usually classified along with TTP as “TTP/HUS”
 Has fewer neurologic sequelae, more renal
manifestations.
 More abdominal pain in symptoms
 Usually precipitated by diarrheal illness,
especially E. coli O157:H7 („Shigatoxin“) or
Shigella
 Seen more in pediatric patients, usually has
better prognosis. May respond less well to
plasma exchange.
Thrombocytopathy
 Congenital/inherited: rare
 Acquired: frequent
Congenital/inherited thrombocytopathy
 Bernard – Soulier´s syndrome
AR inehritance
GP Ib/IX defect
von Willebrand´s factor not
bound
adhesivity defective
Clinically: bleeding of „platelet type“, may be
dengerous and fatal
Dg lab: giant PLT in the blood smear, often
thromocytopenia, abnormal PLT aggregation with
Ristocetin. Negative reaction with anti GP Ib/IX Ab
Therapy: Symptomatic + DDAVP, rF VIIa
 Glanzman´s thrombasthenia
AR inheritance
Defect ib GPIIb/IIIa
fibrinogen not bound
aggregation defective
Clinically: no spontenous bleeding but after
invasion: surgery, dental, delivery, etc.
Dg lab: morfology and No. of PLT normal but
aggregation with ADP, epineprine, kolagen
and thrombin affected
Th: symptomatic + rFVIIa
PLT secretory dysfunction
 Chediak-Higashi´s sy, Wiskott-Aldrich´s sy,
Hermansky-Pudlak´s sy
Defects of δ and α granules
 Aspirine-like disease: realease from granules
defect
Dg lab: pathology in PLT aggregation with
colagen, arachidonic acid, ADP.
Th: Symptomatic (thrombocytes), DDAVP,
rFVIIa
Acquired thrombocytopathy
1. Diseases accociated with thrombocytopathy:
 Myeloprolipherative diseases
 Myelodysplastic syndrome
 Leukemias + Lymphoprolipherative disease
 Paraproteinemia
 Renal insufficiency
 Liver failure
 Autoimmune diseases
 Excorporeal circulation
2. Medication-related thrombocytopathy
 Met. arach. acid involved: acetylsalicylic ac.,
corticosteroids, NSA (ibuprofen, indomethacine,
phenylbutasone, thromboxane antagonists, etc.)
 PLT cAMP: dipyridamol, theofylin, phospohodiesterase
inhibitors,
 Clopidogrel (Plavix, Thrombex) ADP receptor
blocade
GPIIb/IIIa inactivation aggregation
 Other: penicillin, cephalosporins, dextran, tricyclic
antidepressants, antihistamins, betablockers, Ca antagonists,
ticlopidin, vitE, UFH, etc.
Thrombocytosis
 PLT > 450 x109/l
 Clonal thrombocytosis = ET (essential

-
thrombocythaemia, PMF, PV, CML)
Reactive thrombocytosis:
Bacterial infections: osteomyelitis,
pneumonia, TBC,
Postsplenectomy thrombocytosis
Iron defficiency
Bleeding
Th: if >700 x109/l consider antiaggregation
Thank You very much