Platelet refractoriness to classical agonists in a child with essential thrombocythemia.
BACKGROUND
Essential thrombocythemia is a rare disease during childhood. Platelet morphological abnormalities are frequent and defects in platelet function tests, mainly hypoaggregation, occur.


METHODS
An incidental diagnosis of essential thrombocythemia was established in a 9-year-old boy with a platelet count of 2050 x 10(9)/l. His platelets were studied for aggregation defects with four classical agonists employing optical aggregometry.


RESULTS
Aggregation ranged from 5% for adrenaline, 8% for collagen, 12% for ristocetin, to 25% with adenosine diphosphate, followed by complete disaggregation.


CONCLUSIONS
Platelet refractoriness to classical agonists, probably compounded by platelet GPIb deficiency, was documented. The differential diagnosis is discussed.
Jaime-Perez
Jose Carlos
JC
Autonomous University of Nuevo Leon, Monterrey, Mexico. carjaime@hotmail.com
Gomez-Almaguer
David
D
D000244:Adenosine Diphosphate / Q000494:pharmacology; D001792:Blood Platelets / Q000187:drug effects* / Q000473:pathology; D002648:Child; D003094:Collagen / Q000494:pharmacology; D004351:Drug Resistance; D004837:Epinephrine / Q000494:pharmacology; D006801:Humans; D008297:Male; D010974:Platelet Aggregation / Q000187:drug effects; D010979:Platelet Function Tests; D012310:Ristocetin / Q000494:pharmacology; D013920:Thrombocythemia, Essential / Q000097:blood*
D012310:Ristocetin; D000244:Adenosine Diphosphate; D003094:Collagen; D004837:Epinephrine