Primary thrombocythaemia in childhood: Symptomatic episodes and their relationship thromboxane A2, 6-keto-PGE1 and 12-hydroxy-eicosatetraenoic acid production: A case report

In a child with primary thrombocythaemia, observations have been made over a period of five years, during which, transient apparently thrombotic events occurred in the central nervous system on several occasions. Spontaneous platelet aggregation was noted and deaggregation took place even after exposure to ADP in vitro. Associated findings included pronounced elevation in plasma levels of 6-keto-PGF1 alpha and 6-keto-PGE1, the latter described for the first time. Production of 12-HETE by platelets was markedly reduced, probably reflecting lipoxygenase deficiency which has been reported in other myeloproliferative disorders. It has been suggested that 12-HETE is a natural inhibitor of thromboxane synthetase, so the further finding of enormous generation of TxA2, measured as TxB2, by this patient's platelets may be explicable. It is suggested that the increase in TxA2 is responsible for spontaneous platelet aggregation. In response to these massive events, there is a production of 6-keto-PGE1 which in turn, promotes platelet deaggregation. Administration of aspirin resulted in symptomatic relief and complete inhibition of TxB2 production.