Document Type : Research Articles
Department of Internal Medicine, Chiang Rai Prachanukroh Hospital, Chiang Rai, Thailand.
Division of Hematology, Department of Internal Medicine, Faculty of Medicine, Chiang Mai University, Chiang Rai, Thailand.
Background: The prognosis and management of primary thrombocytosis (PT) and secondary thrombocytosis (ST)
are different. This study aims to evaluate the role of platelet function tests by light transmission platelet aggregometry
(LTA), plasma von Willebrand factor antigen (vWF:Ag), ristocetin cofactor activity (vWF:RCo) and inflammatory
markers [erythrocyte sedimentation rate (ESR), C-reactive protein (CRP)] for the differentiation between PT and ST.
Methods: This prospective study was carried out in patients with platelet counts greater than 450 x 109/L. Primary
outcomes were the sensitivity and specificity of platelet function tests by LTA for the differentiation of PT and ST.
Secondary outcomes were sensitivity and specificity of ESR, CRP, vWF:Ag, and vWF:RCo for the differentiation of
PT and ST. Results: Fifty-two patients were enrolled onto the study of which 26 (50%) had PT. The sensitivity and
specificity of epinephrine, collagen, and arachidonic acid (AA) induced abnormal LTA for the differentiation of PT
from ST were sensitivity of 50%, 38.5%, 26.9% and specificity of 88.5%, 100%, 100% respectively. The sensitivity
and specificity of abnormal ESR, CRP, and either abnormal ESR or CRP in the differentiation of ST from PT were
sensitivity of 88.5%, 80.8%, 100% and specificity of 65.4%, 61.5%, 46.2% respectively. The sensitivity and specificity
of low vWF:Ag and vWF:RCo in the differentiation of PT from ST were sensitivity of 7.69%, 42.3% and specificity of
100%, 88.5% respectively. Conclusions: Abnormal platelet function determined by LTA with collagen, AA, epinephrine
had high specificity ratings enabling the differentiation between PT and ST. vWF:RCo, ESR and CRP levels could be
helpful in differentiating between PT and ST.