Hematology II Flashcards by Hermione Granger

Normal platelet count:

140-440K/uL

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Normal platelet lifespan:

7-10 days

destroyed by spleen

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What might cause low platelets (thrombocytopenia):

sequestration, used up in clotting, destruction, failed production, dilution (pregnancy increased blood volume), drugs, liver dz, DIC from cancer or sepsis, HIV, ITP, quinine (tonic water)

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If platelet labs don’t make sense clinically, you should:

retest! platelets are easier to mess up in the lab.

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Initial finding in 10% of HIV diagnosis:

thrombocytopenia

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Most common cause of platelet dysfunction:

aspirin, platelet aggregation inhibitor

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Normal platelet function - 3 A’s:

Adherance
Activation
Aggregation

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What dx do you suspect in pts with lifelong bleeding disorders but normal platelet counts and coag studies?

Hereditary intrinsic platelet disorders

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Autoimmune disorder with increased platelet destruction:

Idiopathic thrombocytopenic purpura (ITP)

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ITP tends to affect what age(s)?

Children and >60yrs

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ITP etiology:

HIV! HEP C!

CMV, drugs, H. Pylori, thyroid disorder, B12/Folate deficiency, autoimmune - SLE

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ITP in children presentation:

acute
self limiting
often triggered by viral illness

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S/sx of ITP:

may be asx
petechiae on [gravity] dependent areas (LE, feet, ankles)
mucosal bleeding
conjunctival hemorrhages
splenomegaly

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Suspected Dx for unexplained low platelet count, otherwise normal CBC?

Idiopathic thrombocytopenia purpura

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Compare vasculitic purpura with hemophilia:

In hemophilia, tend to get deep hematoma and ecchymosis.

ITP has petechiae, particularly in dependent areas

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Thrombocytopenia secondary to splenomegaly seen in:

advanced cirrhosis
myelofibrosis
myeloid metaplasia

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Deficiency in enzyme ADAMTS13 (can’t break down VWF, platelets destroyed by fibrin strands in small vessels):

Thrombotic thrombocytopenic purpura (TTP)

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Etiology of TTP:

children: severe diarrhea with E. Coli 0157:H7
adults: many idiopathic! drug toxicity, pregnancy, autoimmune dz (SLE, scleroderma), AIDS, E. coli, Shiga toxin

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Classic pentad of TTP:

[board exam question, all 5 seen in 5% of pts]

Thrombocytopenia
red cell fragmentation
fever
transient neurologic deficits
kidney failure

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S/sx of TTP:

fever

ischemia: confusion, coma, seizures, headaches, abd pain, arrhythmia, chest pain

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Lab picture of TTP-HUS:

Normal PT, PTT, fibrinogen, D dimer, Coombs
Increase LDH, bilirubin, creatinine
Decreased/absent haptoglobin

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TTP in children with E. Coli 0157:H7:

HUS - hemolytic uremic syndrome

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Hereditary bleeding disorder resulting in impaired synthesis of VWF, prolonged bleeding time, factor 8 deficiency:

Von Willebrand’s Disease

S/sx of VWD:

easy bruising, skin bleeding, prolonged bleeding from mucosal surfaces (oropharyngeal, GI, uterine), menorrhagia, prolonged bleeding after surgery

VWD exam:

look for bruising may be asx ask about family hx

Three tests recommended as VWD screening:

Plasma VWF antigen Plasma VWF activity Factor VIII activity

Arrest of bleeding from an injured vessel:

hemostasis requires vascular, platelet and plasma factors abnormalities result in excessive bleeding or thrombosis

T/F - PT and PTT are assessing platelets in the clotting cascade.

FALSE! these tests examine fibrin and thrombin, but tell you nothing about platelets.

Why might thrombosis occur:

``` Turbulence in a blood vessel Venous stasis - prolonged immobility, bedrest Clotting disorders - factor deficiencies Trauma Medication - oral contraceptives Pregnancy heart failure renal dz cardiac risk factors - smoking, obesity, air pollution, hyperhomocysteinemia ```

What is Virchow's triad:

vascular endothelial injury alterations in blood flow (stasis) alterations in blood constituents

5 most common thrombophilia:

``` prothrombin gene mutation factor V leiden mutation Protein S deficiency Protein C deficiency Antithrombin deficiency ```

DVT &/or PE with no provocation. you suspect: | increased risk with:

Factor V Leiden | oral contraceptives, HRT, pregnancy

Which protein inactivates coat factors Va and VIIIa?

Protein C

Protein C synthesis in the liver is ______ dependent.

Vitamin K

S/sx of protein C deficiency:

venous thromboembolism neonatal purpura fulminans in homozygous or doubly heterozygous newborns warfarin-induced skin necrosis

Cofactor in the protein C system:

Protein S

S/sx of protein S deficiency:

arterial thrombosis | and similar to protein C deficiency

Antithrombin deficiency:

can be fatal to fetus, genetic deficiency,

Hyperhomocysteinemia may be due to:

B12, folate, or B6 deficiency | think about MTHFR mutations

Antiphospholipid antibody syndrom (lupus anticoag):

``` predisposed arterial/venous thrombosis, stroke, DVT, PE prolonged PTT (paradoxical) ```

Widespread activation of the clotting system and consumption of all clotting factors resulting in bleeding out:

Disseminated intravascular coagulation (DIC)

DIC etiology:

septicemia, crush injury, severe head injury, cancer, shock from any cause, heat stroke, burn, snake venom, pregnancy complications, amphetamine OD, ABO incompatibility, liver dz/failure

S/sx of DIC:

``` rapid or slow-evolving persistent bleeding at puncture sites ecchymosis at injection site serious GI bleeding intravascular hemolysis ```

Dx for - central! acute renal/hepatic dysfunction, respiratory dysfunction, shock, thromboembolism, CNS involvement:, petechiae, ecchymoses, blood oozing from mucosa and wound sites (around IV), prolonged PT/PTT/TT, reduced factors

Rapid DIC - decompensated

Dx for - peripheral petechiae, ecchymoses, venous thrombosis, pulmonary emboli, elevated D dimer and fibrin degradation products, normal PT/PTT/TT and factors.

Chronic DIC - compensated

Inherited bleeding disorders with clotting factor deficiencies:

hemophilias

Most common hemophilia:

Hemophilia A - 80% | factor VIII deficient

S/sx of hemophilia:

increased bleeding after circumcision, intracranial hemorrhage in the perinatal period, serious hemorrhage from minor injury, excessive bruising, hematuria, hematoma, hemarthroses - almost pathognomic Most commonly dx >1 yr with learning to walk (falls)

Dx for hemophilia:

PT/PTT, platelet count, assays for factors VIII/IX prolonged PTT normal PT and platelets

too much amyloid, laid down in vessels causing fragility:

amyloidosis

small vessel vasculitis and purpura:

cryoglobulinemia

too much IgG, usually related to immunologic disorder like SLE, vascular purpura, residual brown spots:

hypergammaglobulinemic purpura

elevated plasma IgM, seen in Waldenstrom's macroglobulinemia:

hyperviscosity syndrome

arteriovenous malformations, multiple hemorrhagic lesions on face/lips/oral/nasal muscosas/fingers/toes:

Hereditary hemorrhagic telangiectasia (HHT)

common easy bruising with normal labs, vascular fragility, without significant blood loss:

purpura simples | [responds well to flavonoids!]

persistent dark ecchymoses in elderly patients, usu forearms and hands, without known trauma, resolve leaving brown spot

senile purpura