PLATELET SIZE IN STROKE PATIENTS

Background and Purpose Large platelets are more reactive, produce more prothrombotic factors, and aggregate more easily. Platelet size can b e readily estimated using automated analyzers, although accurate estim ation depends on precise methodology. The disparate results from previ ous studies of mean platelet volume in cerebral ischemia may be explai ned by varying methodology. We have studied these variables using a pr ecise methodology in an unselected group of stroke patients and compar ed them with data from age- and sex-matched control subjects. Methods We studied 58 stroke patients consecutively admitted to a geriatric me dical unit. Platelet variables were measured in the acute (<48 hours a fter stroke) and chronic (>6 months) phases of cerebral ischemia and c ompared with control variables. Control patients, admitted to the same unit, were of similar age and sex and without evidence of acute vascu lar events. Results Mean platelet volume was higher in acute stroke (1 1.3 compared with 10.1 fl,in control subjects; P<.001, Student's t tes t). In addition, platelet count was reduced in stroke patients (255x10 (9)/L) compared with control subjects (299x10(9)/L; P<.01). Repeated m easurements of mean platelet volume and platelet count in available su rvivors showed no significant change from the acute phase. Platelet ch anges did not relate to outcome measured at 6 months. Conclusions With the use of more precise methodology, these findings show that an incr ease in mean platelet volume and a reduction in platelet count are fea tures of both the acute and nonacute phases of cerebral ischemia. It i s possible that these changes precede the vascular event, and further studies are warranted.