Page 529 - Clinical Hematology_ Theory _ Procedures ( PDFDrive )

CHAPTER 26 ■ Disorders of Primary Hemostasis and Thrombosis Vasculature and Platelets 513

T e A erican Society o He ato ogy has estab ishe the Throm botic Throm bocytopenic Purpura

o owing gui e ines or the iagnosis o I P: T ro botic thro bocyto enic ur ura ( P) is a c inica

1. Presence o thro bocyto enia, ack o ane ia un ess b oo syn ro e with a high orta ity rate that is characterize by

oss has occurre , an ack o white ce abnor a ities or ation o icrothro bi in the icrovascu ature.
2. Absence o other causes o thro bocyto enias (e.g., co - C inica signs an sy to s inc u e the o owing:

agen vascu ar iseases or y ho ro i erative isor ers) ■ Severe thro bocyto enia
3. Absence o in ections, articu ar y hu an i uno e - ■ Microangio athic he o ytic ane ia

ciency virus (HIV) ■ Fever

■ Neuro ogic sy to s, or exa e, hea ache, stroke
reatment
■ Rena isease
P ate et trans usions are se o in icate . Surviva ti e

o trans use ate ets is short, but they are i ortant or T e he ato ogica n ings o thro bocyto enia an

contro ing severe he orrhage. T e e cacy o ate ets RBC schistocytes are iagnostic o the isease. Coagu ation

ay i rove i e iate y a er an in usion o intravenous testing wi e onstrate nor a rothro bin an activate

i une g obu in. Intravenous i une g obu in is an artia thro bo astin ti e (AP ) but e evate d- i er

i ortant agent in anaging acute b ee ing an in re ar- an brinogen eve s. P is in contrast to DIC that e on-

ing or roce ures, such as e ivery. reat ent o regnant strates abnor a P an AP .

wo en with I P is a co ex rob e . T ree ty es o P have been i enti e

S enecto y was a we -recognize treat ent or I P or 1. I io athic

ore than 30 years be ore g ucocorticoi s were intro uce in 2. Secon ary

1950, an its success in achieving co ete res onses in two 3. Here itary (U shaw-Schu an)

thir s o atients has been re arkab y consistent or ore

than 60 years. A res onse to s enecto y ty ica y occurs Idiopathic TTP

within severa ays; res onses a er 10 ays are unusua . I io athic P has an unknown etio ogy but has been inke

When treat ent is consi ere or atients with ore severe to an enzy e, ADAM S13 (a disintegrin- ike an meta o-

thro bocyto enia an sy to s, it ust be with the un er- rotease o ain with thro bos on in-ty e oti s), res on-

stan ing that co ete an er anent correction o thro - sib e or the break own o arge von Wi ebran actor (vWF)

bocyto enia is in requent with any thera y. u ti ers. High– o ecu ar-weight vWF in the as a o

atients with P ro otes the aggregation o ate ets in

vivo, which ro uces ost o the c inica sy to s.
NOTE: This is a good time to complete Review Questions Measure ent o ADAM S13 activity is the ost co -

related to preceding content.
on y er or e aboratory assay in a worku o sus ecte

P. In acquire P, the autoantibo ies can inhibit unc-

Increased Utilization of Platelets tion by bin ing to unctiona regions o ADAM S13 (neu-

Intravascu ar coagu ation, vascu ar injury or occ usion, an tra izing) by causing acce erate ADAM S13 c earance

tissue injury can a contribute to the increase uti ization o (nonneutra izing) or through both neutra izing an nonneu-

ate ets. rau a, obstetrica co ications, an icrobia tra izing actions. Labs rare y use antigen assays because o

se sis are exa es o isor ers that can trigger the acce er- their insensitivity to ure y neutra izing inhibitors.

ate consu tion o ate ets. In the case o bacteria se sis,

thro bin-in uce ate et aggregation in vivo contributes Secondary TTP

to the thro bocyto enia. Vascu ar injury (vascu itis) causes Secon ary P is iagnose in atients with a history o

a ecrease in ate ets because o the irect consu tion o e ications, or exa e, quinine, i unosu ressants, or

ate ets at the sites o en othe ia oss without a reciab e so e cytotoxins use in cancer thera y. T is or o P

e etion o c otting actors such as brinogen. has been seen in so e con itions, or exa e, HIV, auto-

i une isor ers, an a ogeneic bone arrow trans ants.
Disseminated Intravascular Coagulation

Upshaw-Schulm an Syndrom e
DIC ra i y consu es ate ets. Sti u ation o ate ets, resu t-

ing in ecrease circu ating ate ets. T ese sti u ate ate ets Upshaw-Schulman syndrome accounts or 5% to 10% o cases.

un ergo sha e change, a hesion, aggregation, an secretion. It is the resu t o inheritance o a e ciency o ADAM S13.

Te contents o the ense a ha-granu es are re ease , ea - T is i er or o P is ani este in chi hoo when

ing to an acquire storage oo e ciency. I in a short erio there is increase vWF, or exa e, inf a ation.

o ti e, erha s a 3-hour s an, ate et counts an brino-

gen eve s ecrease signi cant y in a critica y i atient, DIC Disorders of Platelet Distribution and Dilution

shou be the ri e sus ect as the cause o this change. A ate et istribution isor er can resu t ro a oo ing o

T e overa DIC rocess invo ves coagu ation actors, ate ets in the s een, which is requent i s eno ega y is res-

ate ets, vascu ar en othe ia ce s, brinolysis, an as a ent. T is ty e o thro bocyto enia eve o s when ore than

inhibitors (see Cha ter 28 or a urther iscussion o DIC). a oub e or tri e increase in ate et ro uction is require to