Page 575 - Clinical Hematology_ Theory _ Procedures ( PDFDrive )

CHAPTER 28 ■ Disorders of Hemostasis and Thrombosis: Blood Coagulation Factors, Hypercoagulable State, and Anticoagulant Therapy 559

T e aboratory resu ts in this e ect, as we as those o HMWK- e cient as a ixe with atient as a; a P

other he o hi ias an von Wi ebran ’s isease, are re- is er or e an is co are to a stan ar curve o HMWK

sente in ab e 28.1. versus AP . Inter erence occurs in these assays i atient

is on he arin, hiru in or argatroban, an ossib y ana a-
Factor XII (Hageman Factor) roi . Lower eve s in newborns increase to a u t eve s by age

A unique c inica eature o actor XII e ciency is that 6 onths.

no c inica b ee ing ten encies are a arent. T is autoso-

a recessive is ore co on in Asians than other ethnic

grou s. DISORDERS OF DES RUC ION AND

Factor XII, a as a rotein (g yco rotein), is a c otting CONSUMP ION

actor. A though it is thought that actor XII is nee e or Enhance brin e osits can resu t in thro bosis an a -

ro er b oo c otting, when it is e cient, other b oo c ot- age to organs owing to i e e b oo f ow an ische ia.

ting actors a ear to co ensate or its absence. T e isor- T e brino ytic syste serves as a rotective echanis

er is consi ere to be benign an is usua y asy to atic. against excessive brin e osits by ysing both brin an

A actor e ciency is usua y on y acci enta y iscovere brinogen.

through reo erative b oo tests. B oo coagu ation actors can be estroye in vivo by

A actor XII e ciency ay be sus ecte in atients enzy atic egra ation or by atho ogica activation o

without c inica signs or a revious history o a b ee ing coagu ation with excessive uti ization o the c otting actors.

isor er when the activate thro bo astin ti e (AP ) Enzy atic estruction can resu t ro bites by certain s ecies

or rothro bin (P ) is abnor a . Patients with abnor a o snakes whose veno contains an enzy e that egra es

screening test resu ts but with no b ee ing sy to s can be brinogen to a e ective brin ono er. In vivo activation

screene or antiphospholipid syndrome (APS). o coagu ation by tissue thro bo astin– ike ateria s can

A iagnosis o actor XII e ciency can be con r e by ro uce excessive uti ization o c otting actors. Con itions

a s eci c actor assay.
associate with this consu tion o coagu ation actors

Prekallikrein De ciency inc u e obstetrica co ications, trau a, burns, rostatic
an e vic surgery, shock, a vance a ignancy, se tice ia,
A e ciency o this actor is a so ca e PKK e ciency or an intravascu ar he o ysis.

F etcher actor e ciency. It is cause by ho ozygous or

co oun heterozygous utation in the KLKB1 gene.

F etcher actor e ciency is associate with an inhibitor General Features of Fibrinolysis

to the c ot- ro oting activities o g ass- ike sur aces. No his- Pri ary an secon ary brino ysis are recognize as extre e

tory o an abnor a b ee ing ten ency is note in atients co ications o a variety o intravascu ar an extravascu-

or their a i ies. ar isor ers an ay have i e-threatening consequences.

A ro onge activate artia thro bo astin ti e Pri ary brino ysis is associate with con itions in which

(AP ) an e aye thro bo astin generation but nor- gross activation o the brino ytic echanis with subsequent

a rothro bin ti e (P ) suggest that severe reka ikrein brinogen an coagu ation actor consu tion occurs. T e

e ciency has no c inica y signi cant b ee ing ten ency or i ortant characteristic o ri ary brino ysis is that no evi-

e ect on he ostasis, brino ysis, inf a atory res onses, ence o brin e osition occurs. Pri ary brino ysis occurs

or eukocyte unction. when arge a ounts o as inogen activator enter the circu-

atory syste as a resu t o trau a, surgery, or a ignancies.
High Molecular Weight Kininogen De ciency
A though the sa e c inica con itions ay a so in uce
High Mo ecu ar Weight Kininogen De ciency (HMWK) e - secon ary brino ysis or DIC, the istinction between the

ciency is an autoso a recessive coagu ation e ect. HMWK two is essentia y in the e onstration o brin or ation.

is known by a variety o na es, inc u ing Fitzgera trait, In secon ary brino ysis, excessive c otting an brino-

F aujeac trait, an Wi ia s trait. HMWK is a rare congeni- ytic activity occur. Increase a ounts o brin s it ( eg-

ta isor er inherite as an autoso a recessive trait. Patients ra ation) ro ucts (FSPs/FDPs) an brin ono ers are

with HWMK e ciency o not have a he orrhagic ten ency. etectab e because o the action o thro bin on the brin-

y ica y, the isor er is iscovere in in ivi ua s with an iso- ogen o ecu e. T is brino ytic rocess is on y cause by

ate ro onge activate artia thro bo astin ti e (AP ). excessive c otting; there ore, it is a secon ary con ition.

Fitzgera trait re resents a “true” e ciency o HMWK, Distinguishing between ri ary an secon ary brino ysis

but F aujeac an Wi ia s traits re resent tota kininogen ( ab e 28.8) is i ortant in treat ent.

e ciency, in which both HMWK an ow o ecu ar weight

kininogen (LMWK) are e cient. HMWK an LMWK are Disseminated Intravascular Coagulation

both enco e by the KNG1 gene.

Laboratory n ings inc u e iso ate ro onge activate Etiology

artia thro bo astin ti e (AP ) an negative u us anti- DIC is actua y a co ication or inter e iary hase o

coagu ant (LA). A ixing stu y to test or e ciency uses any iseases an oes not constitute a isor er in itse . It