Page 532 - Clinical Hematology_ Theory _ Procedures ( PDFDrive )

516 PART 7 ■ Principles and Disorders of Hemostasis and Thrombosis

Most cases o E are not inherite . Less co on y, E chro oso e or BCR-ABL assay, an ossib y bone arrow

is inherite in an autoso a o inant attern. T is inher- exa ination, es ecia y in atients with ane ia, acrocyto-

ite con ition is very rare an i ers ro c ona thro bo- sis, euko enia, an /or he atos eno ega y.

cytosis or E . T e reva ence o a i ia thro bocytosis is

not known. T e isor er usua y resents at birth but can

be iscovere at any age. Li e ex ectancy can be a ecte by QUALI A IVE CHARAC ERIS ICS OF

co ications such as thro bosis or bone arrow brosis. PLA ELE S: HROMBOCY OPA HY/

Here itary thro bocytosis is cause by ger ine uta- HROMBOCY HEMIA

tions o the o gene ( HPO) or in the gene or the o

rece tor (MPL). T is con ition ay be cause by a terations I ate ets are nor a in nu ber but ai to er or e ec-

in other genes, not yet i enti e . When the HPO gene is tive y, a ate et ys unction exists. P ate et ys unctions can

utate , there is an increase risk o thro bosis; i the MPL be categorize base on where the e ect exists in one o the

gene is utate , there is requent eve o ent o arrow three hases o nor a ate et unction:

brosis. ■ Initiation hase

Diagnosis is base on the observation o e evate eve s o ■ Extension hase

ate ets an the e i ination o secon ary causes o thro - ■ Conso i ation hase

bocythe ia. High-risk actors wou be i a young atient

has a a i y history o here itary thro bocytosis. Diagnostic In a ition to both an in ivi ua an a i y e ica his-

gui e ines inc u e the o owing: tory, aboratory tests are critica in eter ining a ate et
ys unctiona iagnosis. A key starting oint or the assess-

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■ P ate et counts greater than 450 × 10 /L ent o ate et ys unction is a who e b oo ate et count
■ No essentia thro bocythe ia (no JAK2V617F utation) that nee s to be cross-checke with a eri hera b oo

■ No i enti e cause o secon ary thro bocytosis exa ination to ru e out errors because o acrothro bo-

■ No evi ence o MDS cytes or ate et aggregates. Laboratory assays o ate et

■ No bone arrow or karyoty ing evi ence o acute ye oi unction inc u e ru ing out abnor a ities in c otting ac-
euke ia tors that can be one by er or ing activate AP , P ,

Genetic testing is require to con r the iagnosis. an thro bin ti e assays (see Cha ter 32). Fo ow-u
assays can inc u e the in requent y use b ee ing ti e ro-

Reactive Throm bocytosis (Secondary ce ure an ate et aggregation, ate et a hesiveness, an

Throm bocythem ia) anti ate et antibo y assays. Assess ent o vWF is i or-

Secon ary thro bocytosis: thro bocytosis because o an tant because this abnor a ity is uch ore co on than

externa cause; the seru eve o o is requent y e evate . ate et ys unction isor ers an creates a si i ar b ee -

Secon ary thro bocytosis is usua y acquire : ai ents ing icture.

resu ting in e evate ate et counts inc u e inf a ation, T ree se arate categories o ate et ys unctions can be

iron e ciency, an as enia. In rare cases, secon ary thro - i enti e base on etio ogy ( ab e 26.3). T ese inc u e the

bocytosis is here itary ( a i ia ). ore co on acquire causes an the ess requent here i-

Many atients with thro bocytosis have reactive thro - tary causes. Disor ers within these categories can be i enti-

bocytosis. Reactive thro bocytosis ay be observe in a e using s eci c aboratory tests ( ab e 26.4). Hy eractive

variety o isor ers an con itions, inc u ing iron e ciency ate ets associate with hy ercoagu abi ity an thro -

ane ia, chronic inf a atory isor ers, chronic in ections, bosis ake u an a itiona category o abnor a ate et

rugs, a ignancies such as Ho gkin’s y ho a an non- unction.

Ho gkin’s y ho a, reboun thro bocytosis o owing

treat ent o i uno ogica thro bocyto enic ur ura,

ernicious ane ia, iscontinuance o ye osu ressive Categories of Platelet

rugs, acute b oo oss, exercise, an MDS. T ro bocytosis TABLE 26.3 Dysfunctions

ay a so be seen in autoimmune hemolytic anemia.

A ter s enecto y, increases are note because o the Type Etiology Typical Disorders

oss o the s een. As the bone arrow a justs to new

require ents, ate et nu bers rogressive y return to Acquired Blood plasma Uremia, pernicious

nor a . inhibitor anemia, liver disease

With secon ary thro bocytosis, the ate et count is usu- Drug induced Aspirin

a y ess than 1000 × 10 /L, an the cause ay be obvious Hereditary Defect of connective von Willebrand’s
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ro the history an hysica exa ination ( erha s with tissue or coagulation disease

con r atory testing). CBC an eri hera b oo s ear factors

shou he suggest iron e ciency or he o ysis. I a cause o Bernard-Soulier syn-

secon ary thro bocythe ia is not obvious, atients shou Structural or bio- drome, lanzmann’s

be eva uate or a ye o ro i erative isor er. Such eva ua- chemical defects of hrombasthenia

tion ay inc u e cytogenetic stu ies, inc u ing Phi a e hia platelets