Internal Medicine

0521779407-C03 CUNY1086/Karliner 0 521 77940 7 June 4, 2007 20:54

Congenital Qualitative Platelet Disorders 391

tests

Laboratory

■CBC; PT; PTT

■Bleeding time

■Review platelet & white cell size/morphology on peripheral smear &

mean platelet volume

■Platelet aggregation studies: standard & low-dose ADP, epinephrine,

collagen, arachidonic acid, thrombin; ristocetin agglutination; ADP:

ATP ratio; ATP &/or serotonin release

Other Tests

■Platelet electron micrographs

■Flow cytometry using antibodies to potentially missing surface pro-

teins

differential diagnosis

■Rule out vWd & acquired defects (aspirin ingestion), which are more

frequent

■Glanzmann thrombasthenia: autosomal recessive; normal platelet

count; abnormal platelet aggregation studies w/ all agonists, except

ristocetin; absence/defect of platelet alpha IIb/beta 3 receptors

■Bernard-Soulier syndrome: autosomal recessive; mild thrombo-

cytopenia w/ large platelets; normal aggregation studies except

ristocetin; absence of platelet GPIb/IX/V receptor

■Wiskott-Aldrich syndrome: X-linked recessive, occasionally auto-

somal recessive; thrombocytopenia w/ small platelets, eczema,

immunodeficiency; absence of isohemagglutinins, poor lympho-

cyte mitogenic response, decreased IgM, increased IgE, WAS protein

defect

■Gray platelet syndrome: autosomal recessive; variable platelet aggre-

gation defect; no vWf, fibrinogen, alpha-thromboglobulin or platelet

factor 4 release; gray platelets on Wright stains due to lack of alpha

granules, abnormal platelet electron micrographs; pulmonary fibro-

sis in some; some families w/ risk of acute myelogenous leuke-

mia

■Hermansky-Pudlak syndrome: autosomal recessive, common in

Puerto Ricans; platelet dense granule deficiency w/ abnormal ATP:

ADP ratio; albinism, ceroid deposits in macrophages

■Chediak-Higashi syndrome: autosomal recessive; platelet dense

granule deficiency w/ abnormal ATP:ADP ratio; albinism; giant gran-

ules in neutrophils