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522 PART 7 ■ Principles and Disorders of Hemostasis and Thrombosis

TABLE 26.6 Comparison of Platelet Disorders Versus Blood Coagulation Disorders

Disorders of Platelets or Vessels

Observation (“Purpuric” Disorders) Disorders of Blood Coagulation

Petechiae Characteristic Rare

Deep dissecting hematomas Rare Characteristic

Super cial ecchymosis Characteristic; usually small and multiple Common; usually large and solitary

Hemarthrosis Rare Characteristic

Delayed bleeding Rare Common

Bleeding from super cial Persistent; often profuse Minimal
cuts and scratches

Patient gender Relatively more common in females 80%–90% of hereditary forms occur in females

Positive family history Rare Common

Site of bleeding Skin, mucous membranes, gums, nose, etc. Deep in soft tissue (e.g., joints, muscles)

Bleeding after surgery Immediate, usually mild Delayed (usually 1–2 days), often severe

a arge recursor that consists o a signa e ti e, a ro e - re ease, or stabi ization o VIII:Ag. T ere ore, ecrease ev-

ti e (von Wi ebran antigen II), an the vWF subunit. It e s o vWF ay ro ong the rate o b oo c otting.

has the two ain unctions o regu ating coagu ant activ- Bioassay o actor VIIIc, i unoassay o vWF antigen,

ity (VIII:C) an ai ing in a hesion o ate ets to suben- ristocetin co actor activity.

othe ia ce wa s o owing vesse a age. In circu ating

b oo , vWF is art o a noncova ent bi o ecu ar co ex

with the actor VIII rocoagu ant rotein. T is co ex sta- NOTE: This is a good time to complete the end of chapter

bi izes actor VIII an rotects it ro ra i re ova ro Review Questions related to the preceding content.

the circu ation.

Te vWF ortion re resents ore than 95% o the ass

o the co ex an there ore contro s the o ecu ar stereo- CHAP ER HIGHLIGH S

che istry. T e vWF consists o re eating u ti ers, with

the s a est circu ating u ti er thought to be a i er or Vascular Abnormalities

tetra er. Abnor a b ee ing invo ving the oss o RBCs ro the

Circu ating vWF un ergoes roteo ytic c eavage un er ■
icrocircu ation ex resses itse as ur ura.
hysio ogica con itions; thus, it can be istinguishe Pur ura ay be associate with a variety o vascu ar

ro ate et vWF, which is not roteo yze . T e atho- ■ abnor a ities inc u ing irect en othe ia ce a age,

genesis o von Wi ebran ’s isease is base on quantita- an inherite isease o the connective tissue, ecrease

tive or qua itative abnor a ities, or both, o vWF. When echanica strength o the icrocircu ation, echanica

an abnor a ity is resent, the ecrease actor VIII ro- isru tion o s a venu es, icrothro bi, an vascu ar

coagu ant activity is attributab e to the re uce concentra- a ignancy.

tion o vWF. Vascu itis isor ers inc u e antineutro hi cyto as ic

vWF is essentia in rovi ing the basis or or ation o ■

a nor a ate et thro bus. vWF bin s to s eci c sites on antibo y– ositive vascu itis, cryog obu ine ia, hy er-
ga ag obu ine ic ur ura, an HSP.
the ate et, na e y GPIb an GPIIb/IIIa, whi e concurrent y B ee ing isor ers o erivascu ar tissue inc u e Eh ers-

bin ing to the suben othe iu o a age vesse wa s, ■ Dan os syn ro es, seu oxantho a e asticu , scurvy,

or ing a bri ge. Patients with ecrease eve s o vWF, steroi -in uce ur ura, an so ar ur ura (seni e

es ecia y the arger u ti eric or s, wi ack a equate ur ura).

bri ging action that ro uces ro onge b ee ing ti es.

Qua itative or quantitative abnor a ities o vWF resu t in Quantitative Platelet Disorders

ecrease a hesion an are res onsib e or the b ee ing

9
associate with von Wi ebran ’s isease. ■ T e nor a range o circu ating ate ets is 150 × 10 /L to
9
T e signi cance o vWF in the regu ation o VIII:C 400 × 10 /L.
re ains unc ear. T e increase in VIII:C o owing in usion o ■ I the quantity o ate ets ecreases to eve s be ow the

uri e vWF suggests a ossib e ro e o vWF in the synthesis, re erence, a con ition o thro bocyto enia exists. I the