Page 537 - Clinical Hematology_ Theory _ Procedures ( PDFDrive )

CHAPTER 26 ■ Disorders of Primary Hemostasis and Thrombosis Vasculature and Platelets 521

Laboratory Findings ucocutaneous he orrhages an he aturia, erista sis, an

On a eri hera b oo , ate ets ro atients with easy an s ontaneous bruising. Petechiae are ess co on

this isor er re ain iso ate an o not exhibit c u ing. than in other qua itative ate et isor ers.

E ine hrine, co agen, an thro bin ai to in uce aggrega-

tion. T is resu ts in a ro onge b ee ing ti e in the res- Laboratory Findings

ence o a nor a ate et count, ecrease ate et retention In these isor ers, ate et aggregation with weaker agents,

in g ass bea co u ns, an an absence o a ri ary wave o such as ADP an e ine hrine, is i inishe ( ab e 26.5).

aggregation in res onse to a enosine i hos hate (ADP).

C ot retraction is a so ecrease . von Willebrand’s disease

von Wi ebran ’s isease resu ts ro an abnor a ity in
Hereditary Storage Pool Defect
ri ary he ostasis co bine with i to o erate e -

Etiology ciency o b oo coagu ation actor VIII ( ab e 26.6).

Here itary storage oo e ect is a secon ary aggregation von Wi ebran ’s isease is characterize by abnor a

isor er. Overa , here itary storage oo isor ers are ore ate et unction, ex resse as a ro onge b ee ing ti e.
co on than ri ary aggregation isor ers o the here i- T is is a consistent n ing an ay be acco anie by

tary ate et unction e ects. Here itary as irin- ike e ects ecrease actor VIII rocoagu ant activity.
are a rarer or o secon ary aggregation e ect. vWF circu ates in the b oo in two istinct co art-

In rare instances, storage oo e ects are seen in atients ents, with two ty es o ce s being res onsib e or vWF ro-
with other iseases, inc u ing Wiskott-A rich syn ro e, uction. Vascu ar en othe iu is the ri ary source o the

AR baby syn ro e, Her ansky-Pu ak syn ro e, an synthesis an re ease o as a vWF; the other ty e o ce
Ché iak-Higashi syn ro e. that synthesizes vWF is the egakaryocyte. A roxi ate y

15% o circu ating vWF is ro uce in the egakaryocyte.
Pathophysiology vWF circu ates in ate ets, being store ri ari y in the

Storage granu e abnor a ities, ri ari y an absence o the a ha-granu es, in association with actor VIII rocoagu ant
ense granu es, exist in conjunction with other c inica is- rotein (VIII:Ag). P ate et vWF is re ease ro the a ha-

or ers, such as Ché iak-Higashi syn ro e, Wiskott-A rich granu es by various agonists an subsequent y rebin s to the
syn ro e, an Her ansky-Pu ak syn ro e. GPIIb/IIIa co ex. T e site synthesis o VIII:Ag re ains

unknown, a though the iver is thought to ay an i ortant
Clinical ro e.

C inica eatures are si i ar to other ate et unction e ects. vWF is a arge, a hesive, u ti eric GP resent in
C inica eatures o secon ary aggregation isor ers are as a, ate ets, an suben othe iu . It is synthesize as

TABLE 26.5 Laboratory Pro les of Selected Disorders of Platelet Function

Disorder Laboratory Pro le

Bernard-Soulier syndrome Giant platelets; borderline platelet count; abnormal adhesion; abnormal ristoce-

tin aggregation; normal or decreased thrombin aggregation; other aggregation

responses normal

von Willebrand’s disease Abnormal adhesion; abnormal ristocetin aggregation (type IIB—increased, exhibits

increased sensitivity to low concentrations)

Glanzmann’s thrombasthenia Clot retraction abnormal; bleeding time prolonged; primary aggregation absent with
ADP, thrombin, collagen, epinephrine; PF3 abnormal; ADP primary and secondary;

epinephrine primary and secondary; ristocetin not diagnostic

Storage pool defect Bleeding time prolonged; ADP and epinephrine primary and secondary responses

decreased; arachidonic acid normal or decreased; collagen decreased; thrombin

and ristocetin not diagnostic

Aspirin-like disorder or aspirin Bleeding time prolonged; aggregation primary and secondary; ADP and epinephrine

ingestion; aspirin (aspirin-like disorder); decreased; arachidonic acid decreased; collagen decreased; thrombin and ristoce-

de ciency of cyclooxygenase inhibitor; tin not diagnostic

or thromboxane

ADP, adenosine diphosphate.