Page 526 - Clinical Hematology_ Theory _ Procedures ( PDFDrive )

510 PART 7 ■ Principles and Disorders of Hemostasis and Thrombosis

ch ora henico an che othera eutic agents), che ica s Isoimmune Neonatal T rombocytopenia

(e.g., insectici es), an a coho . In tration o the bone arrow Isoi une neonata thro bocyto enia resu ts ro the

by a ignant ce s in the con itions o etastatic cancer, eu- i unization o a regnant e a e by a eta ate et anti-

ke ia, an Ho gkin’s isease can ro uce a hy o ro i erative gen. T e antigen is inherite by the etus ro the ather an

state. Hy o ro i eration ay a so resu t ro non a ignant is absent on aterna ate ets.

con itions, such as in ections, u us erythe atosus, granu o-

atous isease such as sarcoidosis, an i io athic causes. Trombocytopenia in Pregnancy

Ine ective thro bo oiesis ay resu t in ecrease ate et Both i une an noni une thro bocyto enia ay

ro uction. T ro bocyto enias o this ty e ay be the ani- occur uring regnancy. Pregnant wo en genera y

estation o a nutritiona isor er, such as a e ciency o vita- have ower ate et counts than non regnant wo en.

in B or o ic aci . In these ega ob astic ane ias cause Gestationa thro bocyto enia is cause by a co bina-
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by e ciencies o vita in B or o ic aci , the e ect in thy- tion o he o i ution an increase ate et activation an
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i ine an DNA synthesis a ects egakaryocytes an causes c earance. A ecrease o a roxi ate y 10% in the ate et

ecrease or ine ective thro bo oiesis. Another isor er count is ty ica towar the en o the thir tri ester o

re ate to ine ective thro bo oiesis is iron e ciency ane ia, regnancy.

which usua y resu ts in a ecrease in egakaryocyte size an P ate et autoantibo ies in regnant wo en with I P cross

the su ression o egakaryocyte en o ro i eration an size. the acenta an can ro uce thro bocyto enia an c inica

b ee ing in the newborn in ant.
Disorders of Destruction or Utilization

Increase estruction or uti ization o ate ets ay resu t Heparin-Induced Throm bocytopenia (HIT)

ro a nu ber o echanis s.
He arin-in uce thro bocyto enia (HI ) an associate

Destruction Caused by Im m une Mechanism s, thro botic events, re ative y co on si e e ects o he arin

Antigens, Antibodies, or Com plem ent thera y, can cause substantia orbi ity an orta ity. o
revent these co ications, it has beco e stan ar e i-
Posttrans usion Purpura
ca ractice to onitor ate et counts in atients receiving

Destruction o ate ets can occur as the resu t o inco at- he arin or any exten e erio .

ib e ate ets. A otentia y ata reaction is osttrans usion Seru ro atients with HI contains i unog obu in

ur ura. G (IgG) that, in the resence o s a a ounts o he arin,

activates nor a ate ets an causes the to aggregate an
Drugs
re ease the contents o their granu es, inc u ing serotonin.

Drugs or oreign substances can ro uce ate et estruction. P ate et-activating antibo ies are s eci c not or he arin

Tese rugs inc u e quini ine, su ona i e erivatives, heroin, but or co exes or e between he arin an ate et ac-

or hine, an snake veno . Su ona i e erivative reactions tor 4 (PF4), a he arin-bin ing rotein nor a y oun in

invo ve the interaction o ate et antigens with rug antibo - the a ha-granu es o ate ets. IgG an IgM a so react with

ies. Mor hine reactions invo ve the activation o co e ent. en othe ia ce s coate with PF4 (Fig. 26.7). T is suggests a

echanis o antibo y- e iate vascu ar injury that cou
Bacterial Sepsis
re is ose a atient to thro bosis or DIC when cha enge
Bacteria se sis causes increase estruction o ate ets with he arin.

because o the attach ent o ate ets to bacteria antigen- HI is the ost co on rug-in uce thro bocyto-

antibo y i une co exes. Certain icrobia antigens enia. HI an anti hos ho i i syn ro e (APS) are two

ay attach initia y to ate ets o owe by s eci c antibo ies rothro botic syn ro es in which antibo ies against co -

to the icroorganis . T is echanis has been re orte to exes o charge o ecu es are o un a enta i ortance.

cause the thro bocyto enia that requent y co icates the In the case o APS, the antibo ies are autoantibo ies co -

Plasmodium alciparum ty e o a aria. T ro bocyto enia are to the rug-in uce antibo ies o HI . In both syn-

occurs within 1 to 3 weeks o owing vira in ections (e.g., ro es, IgG antibo ies irecte against ositive y charge

rube a, u s, or chicken ox), arasitic or bacteria in ec- en ogenous roteins, β2-g yco rotein I (GPI) in APS an

tions, or he atitis vaccination. PF4 in HI , are o ajor i ortance.

Immune T rombocytopenia HI is a serious co ication o he arin thera y. T is
con ition is a so ca e “white c ot syn ro e” because it
Antibo ies o either autoi une or isoi une origin ay oses a high risk o otentia y catastro hic venous or arteria

ro uce increase estruction o ate ets. An exa e o thro bosis. T e orta ity rate o atients with thro bosis is

an autoi une thro bocyto enia is neonatal autoimmune a roxi ate y 25%.

thrombocytopenia. T is con ition occurs in in ants born to T ro bocyto enia an thro bosis are the re o inant

others with chronic i une thro bocyto enia (I P) c inica sy to s o HI .

o owing trans acenta assage o aterna IgG ate et wo ty es o HI exist

autoantibo ies. Posttrans usion ur ura is an exa e o

a thro bocyto enia o isoi une origin. Posttrans usion 1. Noni une HI : ty e I

ur ura is a rare or o isoi une thro bocyto enia. 2. I une HI : ty e II